vendor/llvm-project/llvmorg-12-init-17869-g8e464dd76bef

57 files changed, 4705 insertions, 3554 deletions

diff --git a/llvm/lib/ExecutionEngine/ExecutionEngine.cpp b/llvm/lib/ExecutionEngine/ExecutionEngine.cpp
index d8bd671c6661..c8bbf0bcdfda 100644
--- a/llvm/lib/ExecutionEngine/ExecutionEngine.cpp
+++ b/llvm/lib/ExecutionEngine/ExecutionEngine.cpp
@@ -53,11 +53,6 @@ ExecutionEngine *(*ExecutionEngine::MCJITCtor)(
     std::shared_ptr<LegacyJITSymbolResolver> Resolver,
     std::unique_ptr<TargetMachine> TM) = nullptr;
 
-ExecutionEngine *(*ExecutionEngine::OrcMCJITReplacementCtor)(
-    std::string *ErrorStr, std::shared_ptr<MCJITMemoryManager> MemMgr,
-    std::shared_ptr<LegacyJITSymbolResolver> Resolver,
-    std::unique_ptr<TargetMachine> TM) = nullptr;
-
 ExecutionEngine *(*ExecutionEngine::InterpCtor)(std::unique_ptr<Module> M,
                                                 std::string *ErrorStr) =nullptr;
 
@@ -476,8 +471,7 @@ EngineBuilder::EngineBuilder() : EngineBuilder(nullptr) {}
 
 EngineBuilder::EngineBuilder(std::unique_ptr<Module> M)
     : M(std::move(M)), WhichEngine(EngineKind::Either), ErrorStr(nullptr),
-      OptLevel(CodeGenOpt::Default), MemMgr(nullptr), Resolver(nullptr),
-      UseOrcMCJITReplacement(false) {
+      OptLevel(CodeGenOpt::Default), MemMgr(nullptr), Resolver(nullptr) {
 // IR module verification is enabled by default in debug builds, and disabled
 // by default in release builds.
 #ifndef NDEBUG
@@ -540,12 +534,7 @@ ExecutionEngine *EngineBuilder::create(TargetMachine *TM) {
     }
 
     ExecutionEngine *EE = nullptr;
-    if (ExecutionEngine::OrcMCJITReplacementCtor && UseOrcMCJITReplacement) {
-      EE = ExecutionEngine::OrcMCJITReplacementCtor(ErrorStr, std::move(MemMgr),
-                                                    std::move(Resolver),
-                                                    std::move(TheTM));
-      EE->addModule(std::move(M));
-    } else if (ExecutionEngine::MCJITCtor)
+    if (ExecutionEngine::MCJITCtor)
       EE = ExecutionEngine::MCJITCtor(std::move(M), ErrorStr, std::move(MemMgr),
                                       std::move(Resolver), std::move(TheTM));
 
diff --git a/llvm/lib/ExecutionEngine/IntelJITEvents/IntelJITEventListener.cpp b/llvm/lib/ExecutionEngine/IntelJITEvents/IntelJITEventListener.cpp
index 1ebc820a8b49..3f75012f5cf9 100644
--- a/llvm/lib/ExecutionEngine/IntelJITEvents/IntelJITEventListener.cpp
+++ b/llvm/lib/ExecutionEngine/IntelJITEvents/IntelJITEventListener.cpp
@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "IntelJITEventsWrapper.h"
+#include "ittnotify.h"
 #include "llvm-c/ExecutionEngine.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/CodeGen/MachineFunction.h"
@@ -36,6 +37,86 @@ using namespace llvm::object;
 
 namespace {
 
+class IntelIttnotifyInfo {
+  std::string ModuleName;
+  std::vector<std::string> SectionNamesVector;
+  std::vector<__itt_section_info> SectionInfoVector;
+  __itt_module_object *ModuleObject;
+  IntelJITEventsWrapper &WrapperRef;
+
+public:
+  IntelIttnotifyInfo(IntelJITEventsWrapper &Wrapper)
+      : ModuleObject(NULL), WrapperRef(Wrapper){};
+  ~IntelIttnotifyInfo() { delete ModuleObject; };
+
+  void setModuleName(const char *Name) { ModuleName = std::string(Name); }
+
+  const char *getModuleName() { return ModuleName.c_str(); }
+
+  void setModuleObject(__itt_module_object *ModuleObj) {
+    ModuleObject = ModuleObj;
+  }
+
+  __itt_module_object *getModuleObject() { return ModuleObject; }
+
+  __itt_section_info *getSectionInfoVectorBegin() {
+    if (SectionInfoVector.size())
+      return &SectionInfoVector[0];
+    return NULL;
+  }
+
+  void reportSection(llvm::IttEventType EventType, const char *SectionName,
+                     unsigned int SectionSize) {
+    WrapperRef.iJitIttNotifyInfo(EventType, SectionName, SectionSize);
+  }
+
+  int fillSectionInformation(const ObjectFile &Obj,
+                             const RuntimeDyld::LoadedObjectInfo &L) {
+
+    int SectionCounter = 0;
+
+    for (auto &Section : Obj.sections()) {
+      uint64_t SectionLoadAddr = L.getSectionLoadAddress(Section);
+      if (SectionLoadAddr) {
+        object::ELFSectionRef ElfSection(Section);
+
+        __itt_section_info SectionInfo;
+        memset(&SectionInfo, 0, sizeof(SectionInfo));
+        SectionInfo.start_addr = reinterpret_cast<void *>(SectionLoadAddr);
+        SectionInfo.file_offset = ElfSection.getOffset();
+        SectionInfo.flags = ElfSection.getFlags();
+
+        StringRef SectionName("");
+        auto SectionNameOrError = ElfSection.getName();
+        if (SectionNameOrError)
+          SectionName = *SectionNameOrError;
+
+        SectionNamesVector.push_back(SectionName.str());
+        SectionInfo.size = ElfSection.getSize();
+        reportSection(llvm::LoadBinarySection, SectionName.str().c_str(),
+                      SectionInfo.size);
+
+        if (ElfSection.isBSS()) {
+          SectionInfo.type = itt_section_type_bss;
+        } else if (ElfSection.isData()) {
+          SectionInfo.type = itt_section_type_data;
+        } else if (ElfSection.isText()) {
+          SectionInfo.type = itt_section_type_text;
+        }
+        SectionInfoVector.push_back(SectionInfo);
+        ++SectionCounter;
+      }
+    }
+    // Hereinafter: don't change SectionNamesVector content to avoid vector
+    // reallocation - reallocation invalidates all the references, pointers, and
+    // iterators referring to the elements in the sequence.
+    for (int I = 0; I < SectionCounter; ++I) {
+      SectionInfoVector[I].name = SectionNamesVector[I].c_str();
+    }
+    return SectionCounter;
+  }
+};
+
 class IntelJITEventListener : public JITEventListener {
   typedef DenseMap<void*, unsigned int> MethodIDMap;
 
@@ -48,6 +129,8 @@ class IntelJITEventListener : public JITEventListener {
   ObjectMap  LoadedObjectMap;
   std::map<ObjectKey, OwningBinary<ObjectFile>> DebugObjects;
 
+  std::map<ObjectKey, std::unique_ptr<IntelIttnotifyInfo>> KeyToIttnotify;
+
 public:
   IntelJITEventListener(IntelJITEventsWrapper* libraryWrapper) {
       Wrapper.reset(libraryWrapper);
@@ -95,146 +178,205 @@ static iJIT_Method_Load FunctionDescToIntelJITFormat(
   return Result;
 }
 
+int getBackwardCompatibilityMode() {
+
+  char *BackwardCompatibilityEnv = getenv("INTEL_JIT_BACKWARD_COMPATIBILITY");
+  int BackwardCompatibilityMode = 0;
+  if (BackwardCompatibilityEnv) {
+    StringRef(BackwardCompatibilityEnv)
+        .getAsInteger(10, BackwardCompatibilityMode);
+  }
+  return BackwardCompatibilityMode;
+}
+
 void IntelJITEventListener::notifyObjectLoaded(
     ObjectKey Key, const ObjectFile &Obj,
     const RuntimeDyld::LoadedObjectInfo &L) {
 
-  OwningBinary<ObjectFile> DebugObjOwner = L.getObjectForDebug(Obj);
-  const ObjectFile *DebugObj = DebugObjOwner.getBinary();
-  if (!DebugObj)
-    return;
+  int BackwardCompatibilityMode = getBackwardCompatibilityMode();
+  if (BackwardCompatibilityMode == 0) {
+    if (Obj.isELF()) {
+      std::unique_ptr<IntelIttnotifyInfo> ModuleIttnotify =
+          std::make_unique<IntelIttnotifyInfo>(*Wrapper);
+      ModuleIttnotify->setModuleName(
+          StringRef(llvm::utohexstr(
+                        MD5Hash(Obj.getMemoryBufferRef().getBuffer()), true))
+              .str()
+              .c_str());
 
-  // Get the address of the object image for use as a unique identifier
-  const void* ObjData = DebugObj->getData().data();
-  std::unique_ptr<DIContext> Context = DWARFContext::create(*DebugObj);
-  MethodAddressVector Functions;
+      __itt_module_object *ModuleObject = new __itt_module_object();
+      ModuleObject->module_name = ModuleIttnotify->getModuleName();
+      ModuleObject->module_size = Obj.getMemoryBufferRef().getBufferSize();
+      Wrapper->iJitIttNotifyInfo(llvm::LoadBinaryModule,
+                                 ModuleObject->module_name,
+                                 ModuleObject->module_size);
+      ModuleObject->module_type = __itt_module_type_elf;
+      ModuleObject->section_number =
+          ModuleIttnotify->fillSectionInformation(Obj, L);
+      ModuleObject->module_buffer =
+          (void *)const_cast<char *>(Obj.getMemoryBufferRef().getBufferStart());
+      ModuleObject->module_id =
+          __itt_id_make((void *)&(*ModuleObject), ModuleObject->module_size);
+      ModuleObject->section_array =
+          ModuleIttnotify->getSectionInfoVectorBegin();
+      ModuleIttnotify->setModuleObject(ModuleObject);
 
-  // Use symbol info to iterate functions in the object.
-  for (const std::pair<SymbolRef, uint64_t> &P : computeSymbolSizes(*DebugObj)) {
-    SymbolRef Sym = P.first;
-    std::vector<LineNumberInfo> LineInfo;
-    std::string SourceFileName;
+      __itt_module_load_with_sections(ModuleObject);
 
-    Expected<SymbolRef::Type> SymTypeOrErr = Sym.getType();
-    if (!SymTypeOrErr) {
-      // TODO: Actually report errors helpfully.
-      consumeError(SymTypeOrErr.takeError());
-      continue;
+      KeyToIttnotify[Key] = std::move(ModuleIttnotify);
     }
-    SymbolRef::Type SymType = *SymTypeOrErr;
-    if (SymType != SymbolRef::ST_Function)
-      continue;
+  } else if (BackwardCompatibilityMode == 1) {
 
-    Expected<StringRef> Name = Sym.getName();
-    if (!Name) {
-      // TODO: Actually report errors helpfully.
-      consumeError(Name.takeError());
-      continue;
-    }
+    OwningBinary<ObjectFile> DebugObjOwner = L.getObjectForDebug(Obj);
+    const ObjectFile *DebugObj = DebugObjOwner.getBinary();
+    if (!DebugObj)
+      return;
 
-    Expected<uint64_t> AddrOrErr = Sym.getAddress();
-    if (!AddrOrErr) {
-      // TODO: Actually report errors helpfully.
-      consumeError(AddrOrErr.takeError());
-      continue;
-    }
-    uint64_t Addr = *AddrOrErr;
-    uint64_t Size = P.second;
+    // Get the address of the object image for use as a unique identifier
+    const void *ObjData = DebugObj->getData().data();
+    std::unique_ptr<DIContext> Context = DWARFContext::create(*DebugObj);
+    MethodAddressVector Functions;
 
-    auto SecOrErr = Sym.getSection();
-    if (!SecOrErr) {
-      // TODO: Actually report errors helpfully.
-      consumeError(SecOrErr.takeError());
-      continue;
-    }
-    object::section_iterator Sec = *SecOrErr;
-    if (Sec == Obj.section_end())
-      continue;
-    uint64_t Index = Sec->getIndex();
+    // Use symbol info to iterate functions in the object.
+    for (const std::pair<SymbolRef, uint64_t> &P :
+         computeSymbolSizes(*DebugObj)) {
+      SymbolRef Sym = P.first;
+      std::vector<LineNumberInfo> LineInfo;
+      std::string SourceFileName;
 
-    // Record this address in a local vector
-    Functions.push_back((void*)Addr);
+      Expected<SymbolRef::Type> SymTypeOrErr = Sym.getType();
+      if (!SymTypeOrErr) {
+        // TODO: Actually report errors helpfully.
+        consumeError(SymTypeOrErr.takeError());
+        continue;
+      }
+      SymbolRef::Type SymType = *SymTypeOrErr;
+      if (SymType != SymbolRef::ST_Function)
+        continue;
 
-    // Build the function loaded notification message
-    iJIT_Method_Load FunctionMessage =
-      FunctionDescToIntelJITFormat(*Wrapper, Name->data(), Addr, Size);
-    DILineInfoTable Lines =
-      Context->getLineInfoForAddressRange({Addr, Index}, Size);
-    DILineInfoTable::iterator Begin = Lines.begin();
-    DILineInfoTable::iterator End = Lines.end();
-    for (DILineInfoTable::iterator It = Begin; It != End; ++It) {
-      LineInfo.push_back(
-          DILineInfoToIntelJITFormat((uintptr_t)Addr, It->first, It->second));
-    }
-    if (LineInfo.size() == 0) {
-      FunctionMessage.source_file_name = 0;
-      FunctionMessage.line_number_size = 0;
-      FunctionMessage.line_number_table = 0;
-    } else {
-      // Source line information for the address range is provided as
-      // a code offset for the start of the corresponding sub-range and
-      // a source line. JIT API treats offsets in LineNumberInfo structures
-      // as the end of the corresponding code region. The start of the code
-      // is taken from the previous element. Need to shift the elements.
+      Expected<StringRef> Name = Sym.getName();
+      if (!Name) {
+        // TODO: Actually report errors helpfully.
+        consumeError(Name.takeError());
+        continue;
+      }
+
+      Expected<uint64_t> AddrOrErr = Sym.getAddress();
+      if (!AddrOrErr) {
+        // TODO: Actually report errors helpfully.
+        consumeError(AddrOrErr.takeError());
+        continue;
+      }
+      uint64_t Addr = *AddrOrErr;
+      uint64_t Size = P.second;
+
+      auto SecOrErr = Sym.getSection();
+      if (!SecOrErr) {
+        // TODO: Actually report errors helpfully.
+        consumeError(SecOrErr.takeError());
+        continue;
+      }
+      object::section_iterator Sec = *SecOrErr;
+      if (Sec == Obj.section_end())
+        continue;
+      uint64_t Index = Sec->getIndex();
+
+      // Record this address in a local vector
+      Functions.push_back((void *)Addr);
+
+      // Build the function loaded notification message
+      iJIT_Method_Load FunctionMessage =
+          FunctionDescToIntelJITFormat(*Wrapper, Name->data(), Addr, Size);
+      DILineInfoTable Lines =
+          Context->getLineInfoForAddressRange({Addr, Index}, Size);
+      DILineInfoTable::iterator Begin = Lines.begin();
+      DILineInfoTable::iterator End = Lines.end();
+      for (DILineInfoTable::iterator It = Begin; It != End; ++It) {
+        LineInfo.push_back(
+            DILineInfoToIntelJITFormat((uintptr_t)Addr, It->first, It->second));
+      }
+      if (LineInfo.size() == 0) {
+        FunctionMessage.source_file_name = 0;
+        FunctionMessage.line_number_size = 0;
+        FunctionMessage.line_number_table = 0;
+      } else {
+        // Source line information for the address range is provided as
+        // a code offset for the start of the corresponding sub-range and
+        // a source line. JIT API treats offsets in LineNumberInfo structures
+        // as the end of the corresponding code region. The start of the code
+        // is taken from the previous element. Need to shift the elements.
 
-      LineNumberInfo last = LineInfo.back();
-      last.Offset = FunctionMessage.method_size;
-      LineInfo.push_back(last);
-      for (size_t i = LineInfo.size() - 2; i > 0; --i)
-        LineInfo[i].LineNumber = LineInfo[i - 1].LineNumber;
+        LineNumberInfo last = LineInfo.back();
+        last.Offset = FunctionMessage.method_size;
+        LineInfo.push_back(last);
+        for (size_t i = LineInfo.size() - 2; i > 0; --i)
+          LineInfo[i].LineNumber = LineInfo[i - 1].LineNumber;
 
-      SourceFileName = Lines.front().second.FileName;
-      FunctionMessage.source_file_name =
-        const_cast<char *>(SourceFileName.c_str());
-      FunctionMessage.line_number_size = LineInfo.size();
-      FunctionMessage.line_number_table = &*LineInfo.begin();
+        SourceFileName = Lines.front().second.FileName;
+        FunctionMessage.source_file_name =
+            const_cast<char *>(SourceFileName.c_str());
+        FunctionMessage.line_number_size = LineInfo.size();
+        FunctionMessage.line_number_table = &*LineInfo.begin();
+      }
+
+      Wrapper->iJIT_NotifyEvent(iJVM_EVENT_TYPE_METHOD_LOAD_FINISHED,
+                                &FunctionMessage);
+      MethodIDs[(void *)Addr] = FunctionMessage.method_id;
     }
 
-    Wrapper->iJIT_NotifyEvent(iJVM_EVENT_TYPE_METHOD_LOAD_FINISHED,
-                              &FunctionMessage);
-    MethodIDs[(void*)Addr] = FunctionMessage.method_id;
+    // To support object unload notification, we need to keep a list of
+    // registered function addresses for each loaded object.  We will
+    // use the MethodIDs map to get the registered ID for each function.
+    LoadedObjectMap[ObjData] = Functions;
+    DebugObjects[Key] = std::move(DebugObjOwner);
   }
-
-  // To support object unload notification, we need to keep a list of
-  // registered function addresses for each loaded object.  We will
-  // use the MethodIDs map to get the registered ID for each function.
-  LoadedObjectMap[ObjData] = Functions;
-  DebugObjects[Key] = std::move(DebugObjOwner);
 }
 
 void IntelJITEventListener::notifyFreeingObject(ObjectKey Key) {
-  // This object may not have been registered with the listener. If it wasn't,
-  // bail out.
-  if (DebugObjects.find(Key) == DebugObjects.end())
-    return;
 
-  // Get the address of the object image for use as a unique identifier
-  const ObjectFile &DebugObj = *DebugObjects[Key].getBinary();
-  const void* ObjData = DebugObj.getData().data();
+  int BackwardCompatibilityMode = getBackwardCompatibilityMode();
+  if (BackwardCompatibilityMode == 0) {
+    if (KeyToIttnotify.find(Key) == KeyToIttnotify.end())
+      return;
+    __itt_module_unload_with_sections(KeyToIttnotify[Key]->getModuleObject());
+    Wrapper->iJitIttNotifyInfo(
+        llvm::UnloadBinaryModule,
+        KeyToIttnotify[Key]->getModuleObject()->module_name,
+        KeyToIttnotify[Key]->getModuleObject()->module_size);
+    KeyToIttnotify.erase(Key);
+  } else if (BackwardCompatibilityMode == 1) {
+    // This object may not have been registered with the listener. If it wasn't,
+    // bail out.
+    if (DebugObjects.find(Key) == DebugObjects.end())
+      return;
+
+    // Get the address of the object image for use as a unique identifier
+    const ObjectFile &DebugObj = *DebugObjects[Key].getBinary();
+    const void *ObjData = DebugObj.getData().data();
 
-  // Get the object's function list from LoadedObjectMap
-  ObjectMap::iterator OI = LoadedObjectMap.find(ObjData);
-  if (OI == LoadedObjectMap.end())
-    return;
-  MethodAddressVector& Functions = OI->second;
+    // Get the object's function list from LoadedObjectMap
+    ObjectMap::iterator OI = LoadedObjectMap.find(ObjData);
+    if (OI == LoadedObjectMap.end())
+      return;
+    MethodAddressVector &Functions = OI->second;
 
-  // Walk the function list, unregistering each function
-  for (MethodAddressVector::iterator FI = Functions.begin(),
-                                     FE = Functions.end();
-       FI != FE;
-       ++FI) {
-    void* FnStart = const_cast<void*>(*FI);
-    MethodIDMap::iterator MI = MethodIDs.find(FnStart);
-    if (MI != MethodIDs.end()) {
-      Wrapper->iJIT_NotifyEvent(iJVM_EVENT_TYPE_METHOD_UNLOAD_START,
-                                &MI->second);
-      MethodIDs.erase(MI);
+    // Walk the function list, unregistering each function
+    for (MethodAddressVector::iterator FI = Functions.begin(),
+                                       FE = Functions.end();
+         FI != FE; ++FI) {
+      void *FnStart = const_cast<void *>(*FI);
+      MethodIDMap::iterator MI = MethodIDs.find(FnStart);
+      if (MI != MethodIDs.end()) {
+        Wrapper->iJIT_NotifyEvent(iJVM_EVENT_TYPE_METHOD_UNLOAD_START,
+                                  &MI->second);
+        MethodIDs.erase(MI);
+      }
     }
-  }
 
-  // Erase the object from LoadedObjectMap
-  LoadedObjectMap.erase(OI);
-  DebugObjects.erase(Key);
+    // Erase the object from LoadedObjectMap
+    LoadedObjectMap.erase(OI);
+    DebugObjects.erase(Key);
+  }
 }
 
 }  // anonymous namespace.
diff --git a/llvm/lib/ExecutionEngine/IntelJITEvents/IntelJITEventsWrapper.h b/llvm/lib/ExecutionEngine/IntelJITEvents/IntelJITEventsWrapper.h
index 68699c6a2200..088b33b798a3 100644
--- a/llvm/lib/ExecutionEngine/IntelJITEvents/IntelJITEventsWrapper.h
+++ b/llvm/lib/ExecutionEngine/IntelJITEvents/IntelJITEventsWrapper.h
@@ -21,10 +21,18 @@
 
 namespace llvm {
 
+typedef enum {
+  LoadBinaryModule,
+  LoadBinarySection,
+  UnloadBinaryModule,
+  UnloadBinarySection
+} IttEventType;
+
 class IntelJITEventsWrapper {
   // Function pointer types for testing implementation of Intel jitprofiling
   // library
   typedef int (*NotifyEventPtr)(iJIT_JVM_EVENT, void*);
+  typedef int (*IttnotifyInfoPtr)(IttEventType, const char *, unsigned int);
   typedef void (*RegisterCallbackExPtr)(void *, iJIT_ModeChangedEx );
   typedef iJIT_IsProfilingActiveFlags (*IsProfilingActivePtr)(void);
   typedef void (*FinalizeThreadPtr)(void);
@@ -32,6 +40,7 @@ class IntelJITEventsWrapper {
   typedef unsigned int (*GetNewMethodIDPtr)(void);
 
   NotifyEventPtr NotifyEventFunc;
+  IttnotifyInfoPtr IttnotifyInfoFunc;
   RegisterCallbackExPtr RegisterCallbackExFunc;
   IsProfilingActivePtr IsProfilingActiveFunc;
   GetNewMethodIDPtr GetNewMethodIDFunc;
@@ -42,23 +51,22 @@ public:
   }
 
   IntelJITEventsWrapper()
-  : NotifyEventFunc(::iJIT_NotifyEvent),
-    RegisterCallbackExFunc(::iJIT_RegisterCallbackEx),
-    IsProfilingActiveFunc(::iJIT_IsProfilingActive),
-    GetNewMethodIDFunc(::iJIT_GetNewMethodID) {
-  }
+      : NotifyEventFunc(::iJIT_NotifyEvent), IttnotifyInfoFunc(0),
+        RegisterCallbackExFunc(::iJIT_RegisterCallbackEx),
+        IsProfilingActiveFunc(::iJIT_IsProfilingActive),
+        GetNewMethodIDFunc(::iJIT_GetNewMethodID) {}
 
   IntelJITEventsWrapper(NotifyEventPtr NotifyEventImpl,
-                   RegisterCallbackExPtr RegisterCallbackExImpl,
-                   IsProfilingActivePtr IsProfilingActiveImpl,
-                   FinalizeThreadPtr FinalizeThreadImpl,
-                   FinalizeProcessPtr FinalizeProcessImpl,
-                   GetNewMethodIDPtr GetNewMethodIDImpl)
-  : NotifyEventFunc(NotifyEventImpl),
-    RegisterCallbackExFunc(RegisterCallbackExImpl),
-    IsProfilingActiveFunc(IsProfilingActiveImpl),
-    GetNewMethodIDFunc(GetNewMethodIDImpl) {
-  }
+                        IttnotifyInfoPtr IttnotifyInfoImpl,
+                        RegisterCallbackExPtr RegisterCallbackExImpl,
+                        IsProfilingActivePtr IsProfilingActiveImpl,
+                        FinalizeThreadPtr FinalizeThreadImpl,
+                        FinalizeProcessPtr FinalizeProcessImpl,
+                        GetNewMethodIDPtr GetNewMethodIDImpl)
+      : NotifyEventFunc(NotifyEventImpl), IttnotifyInfoFunc(IttnotifyInfoImpl),
+        RegisterCallbackExFunc(RegisterCallbackExImpl),
+        IsProfilingActiveFunc(IsProfilingActiveImpl),
+        GetNewMethodIDFunc(GetNewMethodIDImpl) {}
 
   // Sends an event announcing that a function has been emitted
   //   return values are event-specific.  See Intel documentation for details.
@@ -68,6 +76,13 @@ public:
     return NotifyEventFunc(EventType, EventSpecificData);
   }
 
+  int iJitIttNotifyInfo(IttEventType EventType, const char *Name,
+                        unsigned int Size) {
+    if (!IttnotifyInfoFunc)
+      return -1;
+    return IttnotifyInfoFunc(EventType, Name, Size);
+  }
+
   // Registers a callback function to receive notice of profiling state changes
   void iJIT_RegisterCallbackEx(void *UserData,
                                iJIT_ModeChangedEx NewModeCallBackFuncEx) {
diff --git a/llvm/lib/ExecutionEngine/Interpreter/ExternalFunctions.cpp b/llvm/lib/ExecutionEngine/Interpreter/ExternalFunctions.cpp
index cb1b35d62388..3aa77557862e 100644
--- a/llvm/lib/ExecutionEngine/Interpreter/ExternalFunctions.cpp
+++ b/llvm/lib/ExecutionEngine/Interpreter/ExternalFunctions.cpp
@@ -419,7 +419,7 @@ static GenericValue lle_X_printf(FunctionType *FT,
   char Buffer[10000];
   std::vector<GenericValue> NewArgs;
   NewArgs.push_back(PTOGV((void*)&Buffer[0]));
-  NewArgs.insert(NewArgs.end(), Args.begin(), Args.end());
+  llvm::append_range(NewArgs, Args);
   GenericValue GV = lle_X_sprintf(FT, NewArgs);
   outs() << Buffer;
   return GV;
diff --git a/llvm/lib/ExecutionEngine/JITLink/EHFrameSupport.cpp b/llvm/lib/ExecutionEngine/JITLink/EHFrameSupport.cpp
index f1114e92c360..3602601287f4 100644
--- a/llvm/lib/ExecutionEngine/JITLink/EHFrameSupport.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/EHFrameSupport.cpp
@@ -10,6 +10,8 @@
 #include "EHFrameSupportImpl.h"
 
 #include "llvm/BinaryFormat/Dwarf.h"
+#include "llvm/Config/config.h"
+#include "llvm/ExecutionEngine/Orc/TargetProcess/RegisterEHFrames.h"
 #include "llvm/Support/DynamicLibrary.h"
 
 #define DEBUG_TYPE "jitlink"
@@ -117,10 +119,10 @@ Error EHFrameSplitter::processBlock(LinkGraph &G, Block &B,
 }
 
 EHFrameEdgeFixer::EHFrameEdgeFixer(StringRef EHFrameSectionName,
-                                   Edge::Kind FDEToCIE, Edge::Kind FDEToPCBegin,
-                                   Edge::Kind FDEToLSDA)
-    : EHFrameSectionName(EHFrameSectionName), FDEToCIE(FDEToCIE),
-      FDEToPCBegin(FDEToPCBegin), FDEToLSDA(FDEToLSDA) {}
+                                   unsigned PointerSize, Edge::Kind Delta64,
+                                   Edge::Kind Delta32, Edge::Kind NegDelta32)
+    : EHFrameSectionName(EHFrameSectionName), PointerSize(PointerSize),
+      Delta64(Delta64), Delta32(Delta32), NegDelta32(NegDelta32) {}
 
 Error EHFrameEdgeFixer::operator()(LinkGraph &G) {
   auto *EHFrame = G.findSectionByName(EHFrameSectionName);
@@ -133,6 +135,11 @@ Error EHFrameEdgeFixer::operator()(LinkGraph &G) {
     return Error::success();
   }
 
+  // Check that we support the graph's pointer size.
+  if (G.getPointerSize() != 4 && G.getPointerSize() != 8)
+    return make_error<JITLinkError>(
+        "EHFrameEdgeFixer only supports 32 and 64 bit targets");
+
   LLVM_DEBUG({
     dbgs() << "EHFrameEdgeFixer: Processing " << EHFrameSectionName << "...\n";
   });
@@ -257,7 +264,6 @@ Error EHFrameEdgeFixer::processBlock(ParseContext &PC, Block &B) {
 Error EHFrameEdgeFixer::processCIE(ParseContext &PC, Block &B,
                                    size_t RecordOffset, size_t RecordLength,
                                    size_t CIEDeltaFieldOffset) {
-  using namespace dwarf;
 
   LLVM_DEBUG(dbgs() << "      Record is CIE\n");
 
@@ -328,11 +334,12 @@ Error EHFrameEdgeFixer::processCIE(ParseContext &PC, Block &B,
       uint8_t LSDAPointerEncoding;
       if (auto Err = RecordReader.readInteger(LSDAPointerEncoding))
         return Err;
-      if (LSDAPointerEncoding != (DW_EH_PE_pcrel | DW_EH_PE_absptr))
+      if (!isSupportedPointerEncoding(LSDAPointerEncoding))
         return make_error<JITLinkError>(
             "Unsupported LSDA pointer encoding " +
             formatv("{0:x2}", LSDAPointerEncoding) + " in CIE at " +
             formatv("{0:x16}", CIESymbol.getAddress()));
+      CIEInfo.LSDAPointerEncoding = LSDAPointerEncoding;
       break;
     }
     case 'P': {
@@ -340,7 +347,8 @@ Error EHFrameEdgeFixer::processCIE(ParseContext &PC, Block &B,
       if (auto Err = RecordReader.readInteger(PersonalityPointerEncoding))
         return Err;
       if (PersonalityPointerEncoding !=
-          (DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4))
+          (dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
+           dwarf::DW_EH_PE_sdata4))
         return make_error<JITLinkError>(
             "Unspported personality pointer "
             "encoding " +
@@ -355,12 +363,12 @@ Error EHFrameEdgeFixer::processCIE(ParseContext &PC, Block &B,
       uint8_t FDEPointerEncoding;
       if (auto Err = RecordReader.readInteger(FDEPointerEncoding))
         return Err;
-      if (FDEPointerEncoding != (DW_EH_PE_pcrel | DW_EH_PE_absptr))
+      if (!isSupportedPointerEncoding(FDEPointerEncoding))
         return make_error<JITLinkError>(
-            "Unsupported FDE address pointer "
-            "encoding " +
+            "Unsupported FDE pointer encoding " +
             formatv("{0:x2}", FDEPointerEncoding) + " in CIE at " +
             formatv("{0:x16}", CIESymbol.getAddress()));
+      CIEInfo.FDEPointerEncoding = FDEPointerEncoding;
       break;
     }
     default:
@@ -417,7 +425,7 @@ Error EHFrameEdgeFixer::processFDE(ParseContext &PC, Block &B,
       else
         return CIEInfoOrErr.takeError();
       assert(CIEInfo->CIESymbol && "CIEInfo has no CIE symbol set");
-      B.addEdge(FDEToCIE, RecordOffset + CIEDeltaFieldOffset,
+      B.addEdge(NegDelta32, RecordOffset + CIEDeltaFieldOffset,
                 *CIEInfo->CIESymbol, 0);
     } else {
       LLVM_DEBUG({
@@ -444,11 +452,13 @@ Error EHFrameEdgeFixer::processFDE(ParseContext &PC, Block &B,
     JITTargetAddress PCBeginFieldOffset = RecordReader.getOffset();
     auto PCEdgeItr = BlockEdges.find(RecordOffset + PCBeginFieldOffset);
     if (PCEdgeItr == BlockEdges.end()) {
-      auto PCBeginDelta = readAbsolutePointer(PC.G, RecordReader);
-      if (!PCBeginDelta)
-        return PCBeginDelta.takeError();
-      JITTargetAddress PCBegin =
-          RecordAddress + PCBeginFieldOffset + *PCBeginDelta;
+      auto PCBeginPtrInfo =
+          readEncodedPointer(CIEInfo->FDEPointerEncoding,
+                             RecordAddress + PCBeginFieldOffset, RecordReader);
+      if (!PCBeginPtrInfo)
+        return PCBeginPtrInfo.takeError();
+      JITTargetAddress PCBegin = PCBeginPtrInfo->first;
+      Edge::Kind PCBeginEdgeKind = PCBeginPtrInfo->second;
       LLVM_DEBUG({
         dbgs() << "        Adding edge at "
                << formatv("{0:x16}", RecordAddress + PCBeginFieldOffset)
@@ -457,7 +467,7 @@ Error EHFrameEdgeFixer::processFDE(ParseContext &PC, Block &B,
       auto PCBeginSym = getOrCreateSymbol(PC, PCBegin);
       if (!PCBeginSym)
         return PCBeginSym.takeError();
-      B.addEdge(FDEToPCBegin, RecordOffset + PCBeginFieldOffset, *PCBeginSym,
+      B.addEdge(PCBeginEdgeKind, RecordOffset + PCBeginFieldOffset, *PCBeginSym,
                 0);
       PCBeginBlock = &PCBeginSym->getBlock();
     } else {
@@ -479,38 +489,42 @@ Error EHFrameEdgeFixer::processFDE(ParseContext &PC, Block &B,
                                         " points at external block");
       }
       PCBeginBlock = &EI.Target->getBlock();
-      if (auto Err = RecordReader.skip(PC.G.getPointerSize()))
+      if (auto Err = RecordReader.skip(
+              getPointerEncodingDataSize(CIEInfo->FDEPointerEncoding)))
         return Err;
     }
 
     // Add a keep-alive edge from the FDE target to the FDE to ensure that the
     // FDE is kept alive if its target is.
     assert(PCBeginBlock && "PC-begin block not recorded");
+    LLVM_DEBUG({
+      dbgs() << "        Adding keep-alive edge from target at "
+             << formatv("{0:x16}", PCBeginBlock->getAddress()) << " to FDE at "
+             << formatv("{0:x16}", RecordAddress) << "\n";
+    });
     PCBeginBlock->addEdge(Edge::KeepAlive, 0, FDESymbol, 0);
   }
 
   // Skip over the PC range size field.
-  if (auto Err = RecordReader.skip(PC.G.getPointerSize()))
+  if (auto Err = RecordReader.skip(
+          getPointerEncodingDataSize(CIEInfo->FDEPointerEncoding)))
     return Err;
 
   if (CIEInfo->FDEsHaveLSDAField) {
     uint64_t AugmentationDataSize;
     if (auto Err = RecordReader.readULEB128(AugmentationDataSize))
       return Err;
-    if (AugmentationDataSize != PC.G.getPointerSize())
-      return make_error<JITLinkError>(
-          "Unexpected FDE augmentation data size (expected " +
-          Twine(PC.G.getPointerSize()) + ", got " +
-          Twine(AugmentationDataSize) + ") for FDE at " +
-          formatv("{0:x16}", RecordAddress));
 
     JITTargetAddress LSDAFieldOffset = RecordReader.getOffset();
     auto LSDAEdgeItr = BlockEdges.find(RecordOffset + LSDAFieldOffset);
     if (LSDAEdgeItr == BlockEdges.end()) {
-      auto LSDADelta = readAbsolutePointer(PC.G, RecordReader);
-      if (!LSDADelta)
-        return LSDADelta.takeError();
-      JITTargetAddress LSDA = RecordAddress + LSDAFieldOffset + *LSDADelta;
+      auto LSDAPointerInfo =
+          readEncodedPointer(CIEInfo->LSDAPointerEncoding,
+                             RecordAddress + LSDAFieldOffset, RecordReader);
+      if (!LSDAPointerInfo)
+        return LSDAPointerInfo.takeError();
+      JITTargetAddress LSDA = LSDAPointerInfo->first;
+      Edge::Kind LSDAEdgeKind = LSDAPointerInfo->second;
       auto LSDASym = getOrCreateSymbol(PC, LSDA);
       if (!LSDASym)
         return LSDASym.takeError();
@@ -519,7 +533,7 @@ Error EHFrameEdgeFixer::processFDE(ParseContext &PC, Block &B,
                << formatv("{0:x16}", RecordAddress + LSDAFieldOffset)
                << " to LSDA at " << formatv("{0:x16}", LSDA) << "\n";
       });
-      B.addEdge(FDEToLSDA, RecordOffset + LSDAFieldOffset, *LSDASym, 0);
+      B.addEdge(LSDAEdgeKind, RecordOffset + LSDAFieldOffset, *LSDASym, 0);
     } else {
       LLVM_DEBUG({
         auto &EI = LSDAEdgeItr->second;
@@ -530,7 +544,7 @@ Error EHFrameEdgeFixer::processFDE(ParseContext &PC, Block &B,
           dbgs() << " + " << formatv("{0:x16}", EI.Addend);
         dbgs() << "\n";
       });
-      if (auto Err = RecordReader.skip(PC.G.getPointerSize()))
+      if (auto Err = RecordReader.skip(AugmentationDataSize))
         return Err;
     }
   } else {
@@ -581,23 +595,110 @@ EHFrameEdgeFixer::parseAugmentationString(BinaryStreamReader &RecordReader) {
   return std::move(AugInfo);
 }
 
-Expected<JITTargetAddress>
-EHFrameEdgeFixer::readAbsolutePointer(LinkGraph &G,
-                                      BinaryStreamReader &RecordReader) {
+bool EHFrameEdgeFixer::isSupportedPointerEncoding(uint8_t PointerEncoding) {
+  using namespace dwarf;
+
+  // We only support PC-rel for now.
+  if ((PointerEncoding & 0x70) != DW_EH_PE_pcrel)
+    return false;
+
+  // readEncodedPointer does not handle indirect.
+  if (PointerEncoding & DW_EH_PE_indirect)
+    return false;
+
+  // Supported datatypes.
+  switch (PointerEncoding & 0xf) {
+  case DW_EH_PE_absptr:
+  case DW_EH_PE_udata4:
+  case DW_EH_PE_udata8:
+  case DW_EH_PE_sdata4:
+  case DW_EH_PE_sdata8:
+    return true;
+  }
+
+  return false;
+}
+
+unsigned EHFrameEdgeFixer::getPointerEncodingDataSize(uint8_t PointerEncoding) {
+  using namespace dwarf;
+
+  assert(isSupportedPointerEncoding(PointerEncoding) &&
+         "Unsupported pointer encoding");
+  switch (PointerEncoding & 0xf) {
+  case DW_EH_PE_absptr:
+    return PointerSize;
+  case DW_EH_PE_udata4:
+  case DW_EH_PE_sdata4:
+    return 4;
+  case DW_EH_PE_udata8:
+  case DW_EH_PE_sdata8:
+    return 8;
+  default:
+    llvm_unreachable("Unsupported encoding");
+  }
+}
+
+Expected<std::pair<JITTargetAddress, Edge::Kind>>
+EHFrameEdgeFixer::readEncodedPointer(uint8_t PointerEncoding,
+                                     JITTargetAddress PointerFieldAddress,
+                                     BinaryStreamReader &RecordReader) {
   static_assert(sizeof(JITTargetAddress) == sizeof(uint64_t),
                 "Result must be able to hold a uint64_t");
+  assert(isSupportedPointerEncoding(PointerEncoding) &&
+         "Unsupported pointer encoding");
+
+  using namespace dwarf;
+
+  // Isolate data type, remap absptr to udata4 or udata8. This relies on us
+  // having verified that the graph uses 32-bit or 64-bit pointers only at the
+  // start of this pass.
+  uint8_t EffectiveType = PointerEncoding & 0xf;
+  if (EffectiveType == DW_EH_PE_absptr)
+    EffectiveType = (PointerSize == 8) ? DW_EH_PE_udata8 : DW_EH_PE_udata4;
+
   JITTargetAddress Addr;
-  if (G.getPointerSize() == 8) {
-    if (auto Err = RecordReader.readInteger(Addr))
+  Edge::Kind PointerEdgeKind;
+  switch (EffectiveType) {
+  case DW_EH_PE_udata4: {
+    uint32_t Val;
+    if (auto Err = RecordReader.readInteger(Val))
+      return std::move(Err);
+    Addr = PointerFieldAddress + Val;
+    PointerEdgeKind = Delta32;
+    break;
+  }
+  case DW_EH_PE_udata8: {
+    uint64_t Val;
+    if (auto Err = RecordReader.readInteger(Val))
       return std::move(Err);
-  } else if (G.getPointerSize() == 4) {
-    uint32_t Addr32;
-    if (auto Err = RecordReader.readInteger(Addr32))
+    Addr = PointerFieldAddress + Val;
+    PointerEdgeKind = Delta64;
+    break;
+  }
+  case DW_EH_PE_sdata4: {
+    int32_t Val;
+    if (auto Err = RecordReader.readInteger(Val))
       return std::move(Err);
-    Addr = Addr32;
-  } else
-    llvm_unreachable("Pointer size is not 32-bit or 64-bit");
-  return Addr;
+    Addr = PointerFieldAddress + Val;
+    PointerEdgeKind = Delta32;
+    break;
+  }
+  case DW_EH_PE_sdata8: {
+    int64_t Val;
+    if (auto Err = RecordReader.readInteger(Val))
+      return std::move(Err);
+    Addr = PointerFieldAddress + Val;
+    PointerEdgeKind = Delta64;
+    break;
+  }
+  }
+
+  if (PointerEdgeKind == Edge::Invalid)
+    return make_error<JITLinkError>(
+        "Unspported edge kind for encoded pointer at " +
+        formatv("{0:x}", PointerFieldAddress));
+
+  return std::make_pair(Addr, Delta64);
 }
 
 Expected<Symbol &> EHFrameEdgeFixer::getOrCreateSymbol(ParseContext &PC,
@@ -629,146 +730,21 @@ Expected<Symbol &> EHFrameEdgeFixer::getOrCreateSymbol(ParseContext &PC,
   return PC.G.addAnonymousSymbol(*B, Addr - B->getAddress(), 0, false, false);
 }
 
-// Determine whether we can register EH tables.
-#if (defined(__GNUC__) && !defined(__ARM_EABI__) && !defined(__ia64__) &&      \
-     !(defined(_AIX) && defined(__ibmxl__)) && !defined(__SEH__) &&            \
-     !defined(__USING_SJLJ_EXCEPTIONS__))
-#define HAVE_EHTABLE_SUPPORT 1
-#else
-#define HAVE_EHTABLE_SUPPORT 0
-#endif
-
-#if HAVE_EHTABLE_SUPPORT
-extern "C" void __register_frame(const void *);
-extern "C" void __deregister_frame(const void *);
-
-Error registerFrameWrapper(const void *P) {
-  __register_frame(P);
-  return Error::success();
-}
-
-Error deregisterFrameWrapper(const void *P) {
-  __deregister_frame(P);
-  return Error::success();
-}
-
-#else
-
-// The building compiler does not have __(de)register_frame but
-// it may be found at runtime in a dynamically-loaded library.
-// For example, this happens when building LLVM with Visual C++
-// but using the MingW runtime.
-static Error registerFrameWrapper(const void *P) {
-  static void((*RegisterFrame)(const void *)) = 0;
-
-  if (!RegisterFrame)
-    *(void **)&RegisterFrame =
-        llvm::sys::DynamicLibrary::SearchForAddressOfSymbol("__register_frame");
-
-  if (RegisterFrame) {
-    RegisterFrame(P);
-    return Error::success();
-  }
-
-  return make_error<JITLinkError>("could not register eh-frame: "
-                                  "__register_frame function not found");
-}
-
-static Error deregisterFrameWrapper(const void *P) {
-  static void((*DeregisterFrame)(const void *)) = 0;
-
-  if (!DeregisterFrame)
-    *(void **)&DeregisterFrame =
-        llvm::sys::DynamicLibrary::SearchForAddressOfSymbol(
-            "__deregister_frame");
-
-  if (DeregisterFrame) {
-    DeregisterFrame(P);
-    return Error::success();
-  }
-
-  return make_error<JITLinkError>("could not deregister eh-frame: "
-                                  "__deregister_frame function not found");
-}
-#endif
-
-#ifdef __APPLE__
-
-template <typename HandleFDEFn>
-Error walkAppleEHFrameSection(const char *const SectionStart,
-                              size_t SectionSize,
-                              HandleFDEFn HandleFDE) {
-  const char *CurCFIRecord = SectionStart;
-  const char *End = SectionStart + SectionSize;
-  uint64_t Size = *reinterpret_cast<const uint32_t *>(CurCFIRecord);
-
-  while (CurCFIRecord != End && Size != 0) {
-    const char *OffsetField = CurCFIRecord + (Size == 0xffffffff ? 12 : 4);
-    if (Size == 0xffffffff)
-      Size = *reinterpret_cast<const uint64_t *>(CurCFIRecord + 4) + 12;
-    else
-      Size += 4;
-    uint32_t Offset = *reinterpret_cast<const uint32_t *>(OffsetField);
-
-    LLVM_DEBUG({
-      dbgs() << "Registering eh-frame section:\n";
-      dbgs() << "Processing " << (Offset ? "FDE" : "CIE") << " @"
-             << (void *)CurCFIRecord << ": [";
-      for (unsigned I = 0; I < Size; ++I)
-        dbgs() << format(" 0x%02" PRIx8, *(CurCFIRecord + I));
-      dbgs() << " ]\n";
-    });
-
-    if (Offset != 0)
-      if (auto Err = HandleFDE(CurCFIRecord))
-        return Err;
-
-    CurCFIRecord += Size;
-
-    Size = *reinterpret_cast<const uint32_t *>(CurCFIRecord);
-  }
-
-  return Error::success();
-}
-
-#endif // __APPLE__
-
-Error registerEHFrameSection(const void *EHFrameSectionAddr,
-                             size_t EHFrameSectionSize) {
-#ifdef __APPLE__
-  // On Darwin __register_frame has to be called for each FDE entry.
-  return walkAppleEHFrameSection(static_cast<const char *>(EHFrameSectionAddr),
-                                 EHFrameSectionSize,
-                                 registerFrameWrapper);
-#else
-  // On Linux __register_frame takes a single argument:
-  // a pointer to the start of the .eh_frame section.
-
-  // How can it find the end? Because crtendS.o is linked
-  // in and it has an .eh_frame section with four zero chars.
-  return registerFrameWrapper(EHFrameSectionAddr);
-#endif
-}
-
-Error deregisterEHFrameSection(const void *EHFrameSectionAddr,
-                               size_t EHFrameSectionSize) {
-#ifdef __APPLE__
-  return walkAppleEHFrameSection(static_cast<const char *>(EHFrameSectionAddr),
-                                 EHFrameSectionSize,
-                                 deregisterFrameWrapper);
-#else
-  return deregisterFrameWrapper(EHFrameSectionAddr);
-#endif
-}
-
 EHFrameRegistrar::~EHFrameRegistrar() {}
 
-InProcessEHFrameRegistrar &InProcessEHFrameRegistrar::getInstance() {
-  static InProcessEHFrameRegistrar Instance;
-  return Instance;
+Error InProcessEHFrameRegistrar::registerEHFrames(
+    JITTargetAddress EHFrameSectionAddr, size_t EHFrameSectionSize) {
+  return orc::registerEHFrameSection(
+      jitTargetAddressToPointer<void *>(EHFrameSectionAddr),
+      EHFrameSectionSize);
 }
 
-InProcessEHFrameRegistrar::InProcessEHFrameRegistrar() {}
+Error InProcessEHFrameRegistrar::deregisterEHFrames(
+    JITTargetAddress EHFrameSectionAddr, size_t EHFrameSectionSize) {
+  return orc::deregisterEHFrameSection(
+      jitTargetAddressToPointer<void *>(EHFrameSectionAddr),
+      EHFrameSectionSize);
+}
 
 LinkGraphPassFunction
 createEHFrameRecorderPass(const Triple &TT,
diff --git a/llvm/lib/ExecutionEngine/JITLink/EHFrameSupportImpl.h b/llvm/lib/ExecutionEngine/JITLink/EHFrameSupportImpl.h
index a8cd32c664dc..5e68e72ba18d 100644
--- a/llvm/lib/ExecutionEngine/JITLink/EHFrameSupportImpl.h
+++ b/llvm/lib/ExecutionEngine/JITLink/EHFrameSupportImpl.h
@@ -40,8 +40,9 @@ private:
 /// edges.
 class EHFrameEdgeFixer {
 public:
-  EHFrameEdgeFixer(StringRef EHFrameSectionName, Edge::Kind FDEToCIE,
-                   Edge::Kind FDEToPCBegin, Edge::Kind FDEToLSDA);
+  EHFrameEdgeFixer(StringRef EHFrameSectionName, unsigned PointerSize,
+                   Edge::Kind Delta64, Edge::Kind Delta32,
+                   Edge::Kind NegDelta32);
   Error operator()(LinkGraph &G);
 
 private:
@@ -57,6 +58,8 @@ private:
     CIEInformation(Symbol &CIESymbol) : CIESymbol(&CIESymbol) {}
     Symbol *CIESymbol = nullptr;
     bool FDEsHaveLSDAField = false;
+    uint8_t FDEPointerEncoding = 0;
+    uint8_t LSDAPointerEncoding = 0;
   };
 
   struct EdgeTarget {
@@ -96,14 +99,21 @@ private:
 
   Expected<AugmentationInfo>
   parseAugmentationString(BinaryStreamReader &RecordReader);
-  Expected<JITTargetAddress>
-  readAbsolutePointer(LinkGraph &G, BinaryStreamReader &RecordReader);
+
+  static bool isSupportedPointerEncoding(uint8_t PointerEncoding);
+  unsigned getPointerEncodingDataSize(uint8_t PointerEncoding);
+  Expected<std::pair<JITTargetAddress, Edge::Kind>>
+  readEncodedPointer(uint8_t PointerEncoding,
+                     JITTargetAddress PointerFieldAddress,
+                     BinaryStreamReader &RecordReader);
+
   Expected<Symbol &> getOrCreateSymbol(ParseContext &PC, JITTargetAddress Addr);
 
   StringRef EHFrameSectionName;
-  Edge::Kind FDEToCIE;
-  Edge::Kind FDEToPCBegin;
-  Edge::Kind FDEToLSDA;
+  unsigned PointerSize;
+  Edge::Kind Delta64;
+  Edge::Kind Delta32;
+  Edge::Kind NegDelta32;
 };
 
 } // end namespace jitlink
diff --git a/llvm/lib/ExecutionEngine/JITLink/ELF.cpp b/llvm/lib/ExecutionEngine/JITLink/ELF.cpp
index 6160583b13fe..27eb7d576e2d 100644
--- a/llvm/lib/ExecutionEngine/JITLink/ELF.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/ELF.cpp
@@ -15,6 +15,7 @@
 
 #include "llvm/BinaryFormat/ELF.h"
 #include "llvm/ExecutionEngine/JITLink/ELF_x86_64.h"
+#include "llvm/Object/ELF.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Support/MemoryBuffer.h"
@@ -27,24 +28,63 @@ using namespace llvm;
 namespace llvm {
 namespace jitlink {
 
-void jitLink_ELF(std::unique_ptr<JITLinkContext> Ctx) {
+Expected<uint16_t> readTargetMachineArch(StringRef Buffer) {
+  const char *Data = Buffer.data();
 
-  // We don't want to do full ELF validation here. We just verify it is elf'ish.
-  // Probably should parse into an elf header when we support more than x86 :)
-
-  StringRef Data = Ctx->getObjectBuffer().getBuffer();
-  if (Data.size() < llvm::ELF::EI_MAG3 + 1) {
-    Ctx->notifyFailed(make_error<JITLinkError>("Truncated ELF buffer"));
-    return;
+  if (Data[ELF::EI_DATA] == ELF::ELFDATA2LSB) {
+    if (Data[ELF::EI_CLASS] == ELF::ELFCLASS64) {
+      if (auto File = llvm::object::ELF64LEFile::create(Buffer)) {
+        return File->getHeader().e_machine;
+      } else {
+        return File.takeError();
+      }
+    } else if (Data[ELF::EI_CLASS] == ELF::ELFCLASS32) {
+      if (auto File = llvm::object::ELF32LEFile::create(Buffer)) {
+        return File->getHeader().e_machine;
+      } else {
+        return File.takeError();
+      }
+    }
   }
 
-  if (!memcmp(Data.data(), llvm::ELF::ElfMagic, strlen(llvm::ELF::ElfMagic))) {
-    if (Data.data()[llvm::ELF::EI_CLASS] == ELF::ELFCLASS64) {
-      return jitLink_ELF_x86_64(std::move(Ctx));
-    }
+  return ELF::EM_NONE;
+}
+
+Expected<std::unique_ptr<LinkGraph>>
+createLinkGraphFromELFObject(MemoryBufferRef ObjectBuffer) {
+  StringRef Buffer = ObjectBuffer.getBuffer();
+  if (Buffer.size() < ELF::EI_MAG3 + 1)
+    return make_error<JITLinkError>("Truncated ELF buffer");
+
+  if (memcmp(Buffer.data(), ELF::ElfMagic, strlen(ELF::ElfMagic)) != 0)
+    return make_error<JITLinkError>("ELF magic not valid");
+
+  Expected<uint16_t> TargetMachineArch = readTargetMachineArch(Buffer);
+  if (!TargetMachineArch)
+    return TargetMachineArch.takeError();
+
+  switch (*TargetMachineArch) {
+  case ELF::EM_X86_64:
+    return createLinkGraphFromELFObject_x86_64(std::move(ObjectBuffer));
+  default:
+    return make_error<JITLinkError>(
+        "Unsupported target machine architecture in ELF object " +
+        ObjectBuffer.getBufferIdentifier());
   }
+}
 
-  Ctx->notifyFailed(make_error<JITLinkError>("ELF magic not valid"));
+void link_ELF(std::unique_ptr<LinkGraph> G,
+              std::unique_ptr<JITLinkContext> Ctx) {
+  switch (G->getTargetTriple().getArch()) {
+  case Triple::x86_64:
+    link_ELF_x86_64(std::move(G), std::move(Ctx));
+    return;
+  default:
+    Ctx->notifyFailed(make_error<JITLinkError>(
+        "Unsupported target machine architecture in ELF link graph " +
+        G->getName()));
+    return;
+  }
 }
 
 } // end namespace jitlink
diff --git a/llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp b/llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp
index 505f03590b6b..2a6b3eb19ded 100644
--- a/llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp
@@ -11,16 +11,204 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ExecutionEngine/JITLink/ELF_x86_64.h"
-#include "JITLinkGeneric.h"
 #include "llvm/ExecutionEngine/JITLink/JITLink.h"
 #include "llvm/Object/ELFObjectFile.h"
+#include "llvm/Support/Endian.h"
+
+#include "BasicGOTAndStubsBuilder.h"
+#include "EHFrameSupportImpl.h"
+#include "JITLinkGeneric.h"
 
 #define DEBUG_TYPE "jitlink"
 
 using namespace llvm;
 using namespace llvm::jitlink;
+using namespace llvm::jitlink::ELF_x86_64_Edges;
+
+namespace {
+
+class ELF_x86_64_GOTAndStubsBuilder
+    : public BasicGOTAndStubsBuilder<ELF_x86_64_GOTAndStubsBuilder> {
+public:
+  static const uint8_t NullGOTEntryContent[8];
+  static const uint8_t StubContent[6];
+
+  ELF_x86_64_GOTAndStubsBuilder(LinkGraph &G)
+      : BasicGOTAndStubsBuilder<ELF_x86_64_GOTAndStubsBuilder>(G) {}
+
+  bool isGOTEdge(Edge &E) const {
+    return E.getKind() == PCRel32GOT || E.getKind() == PCRel32GOTLoad;
+  }
+
+  Symbol &createGOTEntry(Symbol &Target) {
+    auto &GOTEntryBlock = G.createContentBlock(
+        getGOTSection(), getGOTEntryBlockContent(), 0, 8, 0);
+    GOTEntryBlock.addEdge(Pointer64, 0, Target, 0);
+    return G.addAnonymousSymbol(GOTEntryBlock, 0, 8, false, false);
+  }
+
+  void fixGOTEdge(Edge &E, Symbol &GOTEntry) {
+    assert((E.getKind() == PCRel32GOT || E.getKind() == PCRel32GOTLoad) &&
+           "Not a GOT edge?");
+    // If this is a PCRel32GOT then change it to an ordinary PCRel32. If it is
+    // a PCRel32GOTLoad then leave it as-is for now. We will use the kind to
+    // check for GOT optimization opportunities in the
+    // optimizeMachO_x86_64_GOTAndStubs pass below.
+    if (E.getKind() == PCRel32GOT)
+      E.setKind(PCRel32);
+
+    E.setTarget(GOTEntry);
+    // Leave the edge addend as-is.
+  }
+
+  bool isExternalBranchEdge(Edge &E) {
+    return E.getKind() == Branch32 && !E.getTarget().isDefined();
+  }
+
+  Symbol &createStub(Symbol &Target) {
+    auto &StubContentBlock =
+        G.createContentBlock(getStubsSection(), getStubBlockContent(), 0, 1, 0);
+    // Re-use GOT entries for stub targets.
+    auto &GOTEntrySymbol = getGOTEntrySymbol(Target);
+    StubContentBlock.addEdge(PCRel32, 2, GOTEntrySymbol, -4);
+    return G.addAnonymousSymbol(StubContentBlock, 0, 6, true, false);
+  }
+
+  void fixExternalBranchEdge(Edge &E, Symbol &Stub) {
+    assert(E.getKind() == Branch32 && "Not a Branch32 edge?");
+
+    // Set the edge kind to Branch32ToStub. We will use this to check for stub
+    // optimization opportunities in the optimize ELF_x86_64_GOTAndStubs pass
+    // below.
+    E.setKind(Branch32ToStub);
+    E.setTarget(Stub);
+  }
+
+private:
+  Section &getGOTSection() {
+    if (!GOTSection)
+      GOTSection = &G.createSection("$__GOT", sys::Memory::MF_READ);
+    return *GOTSection;
+  }
+
+  Section &getStubsSection() {
+    if (!StubsSection) {
+      auto StubsProt = static_cast<sys::Memory::ProtectionFlags>(
+          sys::Memory::MF_READ | sys::Memory::MF_EXEC);
+      StubsSection = &G.createSection("$__STUBS", StubsProt);
+    }
+    return *StubsSection;
+  }
+
+  StringRef getGOTEntryBlockContent() {
+    return StringRef(reinterpret_cast<const char *>(NullGOTEntryContent),
+                     sizeof(NullGOTEntryContent));
+  }
+
+  StringRef getStubBlockContent() {
+    return StringRef(reinterpret_cast<const char *>(StubContent),
+                     sizeof(StubContent));
+  }
+
+  Section *GOTSection = nullptr;
+  Section *StubsSection = nullptr;
+};
+
+const char *const DwarfSectionNames[] = {
+#define HANDLE_DWARF_SECTION(ENUM_NAME, ELF_NAME, CMDLINE_NAME, OPTION)        \
+  ELF_NAME,
+#include "llvm/BinaryFormat/Dwarf.def"
+#undef HANDLE_DWARF_SECTION
+};
+
+} // namespace
+
+const uint8_t ELF_x86_64_GOTAndStubsBuilder::NullGOTEntryContent[8] = {
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
+const uint8_t ELF_x86_64_GOTAndStubsBuilder::StubContent[6] = {
+    0xFF, 0x25, 0x00, 0x00, 0x00, 0x00};
 
 static const char *CommonSectionName = "__common";
+static Error optimizeELF_x86_64_GOTAndStubs(LinkGraph &G) {
+  LLVM_DEBUG(dbgs() << "Optimizing GOT entries and stubs:\n");
+
+  for (auto *B : G.blocks())
+    for (auto &E : B->edges())
+      if (E.getKind() == PCRel32GOTLoad) {
+        // Replace GOT load with LEA only for MOVQ instructions.
+        constexpr uint8_t MOVQRIPRel[] = {0x48, 0x8b};
+        if (E.getOffset() < 3 ||
+            strncmp(B->getContent().data() + E.getOffset() - 3,
+                    reinterpret_cast<const char *>(MOVQRIPRel), 2) != 0)
+          continue;
+
+        auto &GOTBlock = E.getTarget().getBlock();
+        assert(GOTBlock.getSize() == G.getPointerSize() &&
+               "GOT entry block should be pointer sized");
+        assert(GOTBlock.edges_size() == 1 &&
+               "GOT entry should only have one outgoing edge");
+
+        auto &GOTTarget = GOTBlock.edges().begin()->getTarget();
+        JITTargetAddress EdgeAddr = B->getAddress() + E.getOffset();
+        JITTargetAddress TargetAddr = GOTTarget.getAddress();
+
+        int64_t Displacement = TargetAddr - EdgeAddr + 4;
+        if (Displacement >= std::numeric_limits<int32_t>::min() &&
+            Displacement <= std::numeric_limits<int32_t>::max()) {
+          // Change the edge kind as we don't go through GOT anymore. This is
+          // for formal correctness only. Technically, the two relocation kinds
+          // are resolved the same way.
+          E.setKind(PCRel32);
+          E.setTarget(GOTTarget);
+          auto *BlockData = reinterpret_cast<uint8_t *>(
+              const_cast<char *>(B->getContent().data()));
+          BlockData[E.getOffset() - 2] = 0x8d;
+          LLVM_DEBUG({
+            dbgs() << "  Replaced GOT load wih LEA:\n    ";
+            printEdge(dbgs(), *B, E, getELFX86RelocationKindName(E.getKind()));
+            dbgs() << "\n";
+          });
+        }
+      } else if (E.getKind() == Branch32ToStub) {
+        auto &StubBlock = E.getTarget().getBlock();
+        assert(StubBlock.getSize() ==
+                   sizeof(ELF_x86_64_GOTAndStubsBuilder::StubContent) &&
+               "Stub block should be stub sized");
+        assert(StubBlock.edges_size() == 1 &&
+               "Stub block should only have one outgoing edge");
+
+        auto &GOTBlock = StubBlock.edges().begin()->getTarget().getBlock();
+        assert(GOTBlock.getSize() == G.getPointerSize() &&
+               "GOT block should be pointer sized");
+        assert(GOTBlock.edges_size() == 1 &&
+               "GOT block should only have one outgoing edge");
+
+        auto &GOTTarget = GOTBlock.edges().begin()->getTarget();
+        JITTargetAddress EdgeAddr = B->getAddress() + E.getOffset();
+        JITTargetAddress TargetAddr = GOTTarget.getAddress();
+
+        int64_t Displacement = TargetAddr - EdgeAddr + 4;
+        if (Displacement >= std::numeric_limits<int32_t>::min() &&
+            Displacement <= std::numeric_limits<int32_t>::max()) {
+          E.setKind(Branch32);
+          E.setTarget(GOTTarget);
+          LLVM_DEBUG({
+            dbgs() << "  Replaced stub branch with direct branch:\n    ";
+            printEdge(dbgs(), *B, E, getELFX86RelocationKindName(E.getKind()));
+            dbgs() << "\n";
+          });
+        }
+      }
+
+  return Error::success();
+}
+
+static bool isDwarfSection(StringRef SectionName) {
+  for (auto &DwarfSectionName : DwarfSectionNames)
+    if (SectionName == DwarfSectionName)
+      return true;
+  return false;
+}
 
 namespace llvm {
 namespace jitlink {
@@ -35,7 +223,8 @@ private:
   // Find a better way
   using SymbolTable = object::ELFFile<object::ELF64LE>::Elf_Shdr;
   // For now we just assume
-  std::map<int32_t, Symbol *> JITSymbolTable;
+  using SymbolMap = std::map<int32_t, Symbol *>;
+  SymbolMap JITSymbolTable;
 
   Section &getCommonSection() {
     if (!CommonSection) {
@@ -51,6 +240,16 @@ private:
     switch (Type) {
     case ELF::R_X86_64_PC32:
       return ELF_x86_64_Edges::ELFX86RelocationKind::PCRel32;
+    case ELF::R_X86_64_PC64:
+      return ELF_x86_64_Edges::ELFX86RelocationKind::Delta64;
+    case ELF::R_X86_64_64:
+      return ELF_x86_64_Edges::ELFX86RelocationKind::Pointer64;
+    case ELF::R_X86_64_GOTPCREL:
+    case ELF::R_X86_64_GOTPCRELX:
+    case ELF::R_X86_64_REX_GOTPCRELX:
+      return ELF_x86_64_Edges::ELFX86RelocationKind::PCRel32GOTLoad;
+    case ELF::R_X86_64_PLT32:
+      return ELF_x86_64_Edges::ELFX86RelocationKind::Branch32;
     }
     return make_error<JITLinkError>("Unsupported x86-64 relocation:" +
                                     formatv("{0:d}", Type));
@@ -62,7 +261,7 @@ private:
   object::ELFFile<object::ELF64LE>::Elf_Shdr_Range sections;
   SymbolTable SymTab;
 
-  bool isRelocatable() { return Obj.getHeader()->e_type == llvm::ELF::ET_REL; }
+  bool isRelocatable() { return Obj.getHeader().e_type == llvm::ELF::ET_REL; }
 
   support::endianness
   getEndianness(const object::ELFFile<object::ELF64LE> &Obj) {
@@ -71,7 +270,7 @@ private:
 
   // This could also just become part of a template
   unsigned getPointerSize(const object::ELFFile<object::ELF64LE> &Obj) {
-    return Obj.getHeader()->getFileClass() == ELF::ELFCLASS64 ? 8 : 4;
+    return Obj.getHeader().getFileClass() == ELF::ELFCLASS64 ? 8 : 4;
   }
 
   // We don't technically need this right now
@@ -95,16 +294,12 @@ private:
       auto StrTabSec = Obj.getSection(SecRef.sh_link);
       if (!StrTabSec)
         return StrTabSec.takeError();
-      auto StringTable = Obj.getStringTable(*StrTabSec);
+      auto StringTable = Obj.getStringTable(**StrTabSec);
       if (!StringTable)
         return StringTable.takeError();
 
       for (auto SymRef : *Symbols) {
         Optional<StringRef> Name;
-        uint64_t Size = 0;
-
-        // FIXME: Read size.
-        (void)Size;
 
         if (auto NameOrErr = SymRef.getName(*StringTable))
           Name = *NameOrErr;
@@ -112,16 +307,13 @@ private:
           return NameOrErr.takeError();
 
         LLVM_DEBUG({
-          dbgs() << "  ";
-          if (!Name)
-            dbgs() << "<anonymous symbol>";
-          else
-            dbgs() << *Name;
-          dbgs() << ": value = " << formatv("{0:x16}", SymRef.getValue())
+          dbgs() << "  value = " << formatv("{0:x16}", SymRef.getValue())
                  << ", type = " << formatv("{0:x2}", SymRef.getType())
-                 << ", binding = " << SymRef.getBinding()
-                 << ", size =" << Size;
-          dbgs() << "\n";
+                 << ", binding = " << formatv("{0:x2}", SymRef.getBinding())
+                 << ", size = "
+                 << formatv("{0:x16}", static_cast<uint64_t>(SymRef.st_size))
+                 << ", info = " << formatv("{0:x2}", SymRef.st_info)
+                 << " :" << (Name ? *Name : "<anonymous symbol>") << "\n";
         });
       }
     }
@@ -131,9 +323,19 @@ private:
   Error createNormalizedSections() {
     LLVM_DEBUG(dbgs() << "Creating normalized sections...\n");
     for (auto &SecRef : sections) {
-      auto Name = Obj.getSectionName(&SecRef);
+      auto Name = Obj.getSectionName(SecRef);
       if (!Name)
         return Name.takeError();
+
+      // Skip Dwarf sections.
+      if (isDwarfSection(*Name)) {
+        LLVM_DEBUG({
+          dbgs() << *Name
+                 << " is a debug section: No graph section will be created.\n";
+        });
+        continue;
+      }
+
       sys::Memory::ProtectionFlags Prot;
       if (SecRef.sh_flags & ELF::SHF_EXECINSTR) {
         Prot = static_cast<sys::Memory::ProtectionFlags>(sys::Memory::MF_READ |
@@ -147,8 +349,8 @@ private:
       uint64_t Flags = SecRef.sh_flags;
       uint64_t Alignment = SecRef.sh_addralign;
       const char *Data = nullptr;
-      // TODO: figure out what it is that has 0 size no name and address
-      // 0000-0000
+      // for now we just use this to skip the "undefined" section, probably need
+      // to revist
       if (Size == 0)
         continue;
 
@@ -158,13 +360,13 @@ private:
       LLVM_DEBUG({
         dbgs() << "  " << *Name << ": " << formatv("{0:x16}", Address) << " -- "
                << formatv("{0:x16}", Address + Size) << ", align: " << Alignment
-               << " Flags:" << Flags << "\n";
+               << " Flags: " << formatv("{0:x}", Flags) << "\n";
       });
 
       if (SecRef.sh_type != ELF::SHT_NOBITS) {
         // .sections() already checks that the data is not beyond the end of
         // file
-        auto contents = Obj.getSectionContentsAsArray<char>(&SecRef);
+        auto contents = Obj.getSectionContentsAsArray<char>(SecRef);
         if (!contents)
           return contents.takeError();
 
@@ -178,6 +380,9 @@ private:
         if (SecRef.sh_type == ELF::SHT_SYMTAB)
           // TODO: Dynamic?
           SymTab = SecRef;
+      } else {
+        auto &Section = G->createSection(*Name, Prot);
+        G->createZeroFillBlock(Section, Size, Address, Alignment, 0);
       }
     }
 
@@ -196,21 +401,34 @@ private:
         return make_error<llvm::StringError>("Shouldn't have REL in x64",
                                              llvm::inconvertibleErrorCode());
 
-      auto RelSectName = Obj.getSectionName(&SecRef);
+      auto RelSectName = Obj.getSectionName(SecRef);
       if (!RelSectName)
         return RelSectName.takeError();
-      // Deal with .eh_frame later
-      if (*RelSectName == StringRef(".rela.eh_frame"))
-        continue;
+
+      LLVM_DEBUG({
+        dbgs() << "Adding relocations from section " << *RelSectName << "\n";
+      });
 
       auto UpdateSection = Obj.getSection(SecRef.sh_info);
       if (!UpdateSection)
         return UpdateSection.takeError();
 
-      auto UpdateSectionName = Obj.getSectionName(*UpdateSection);
+      auto UpdateSectionName = Obj.getSectionName(**UpdateSection);
       if (!UpdateSectionName)
         return UpdateSectionName.takeError();
 
+      // Don't process relocations for debug sections.
+      if (isDwarfSection(*UpdateSectionName)) {
+        LLVM_DEBUG({
+          dbgs() << "  Target is dwarf section " << *UpdateSectionName
+                 << ". Skipping.\n";
+        });
+        continue;
+      } else
+        LLVM_DEBUG({
+          dbgs() << "  For target section " << *UpdateSectionName << "\n";
+        });
+
       auto JITSection = G->findSectionByName(*UpdateSectionName);
       if (!JITSection)
         return make_error<llvm::StringError>(
@@ -218,7 +436,7 @@ private:
                 *UpdateSectionName,
             llvm::inconvertibleErrorCode());
 
-      auto Relocations = Obj.relas(&SecRef);
+      auto Relocations = Obj.relas(SecRef);
       if (!Relocations)
         return Relocations.takeError();
 
@@ -229,13 +447,22 @@ private:
           dbgs() << "Relocation Type: " << Type << "\n"
                  << "Name: " << Obj.getRelocationTypeName(Type) << "\n";
         });
-
-        auto Symbol = Obj.getRelocationSymbol(&Rela, &SymTab);
+        auto SymbolIndex = Rela.getSymbol(false);
+        auto Symbol = Obj.getRelocationSymbol(Rela, &SymTab);
         if (!Symbol)
           return Symbol.takeError();
 
         auto BlockToFix = *(JITSection->blocks().begin());
-        auto TargetSymbol = JITSymbolTable[(*Symbol)->st_shndx];
+        auto *TargetSymbol = JITSymbolTable[SymbolIndex];
+
+        if (!TargetSymbol) {
+          return make_error<llvm::StringError>(
+              "Could not find symbol at given index, did you add it to "
+              "JITSymbolTable? index: " + std::to_string(SymbolIndex)
+              + ", shndx: " + std::to_string((*Symbol)->st_shndx) +
+                  " Size of table: " + std::to_string(JITSymbolTable.size()),
+              llvm::inconvertibleErrorCode());
+        }
         uint64_t Addend = Rela.r_addend;
         JITTargetAddress FixupAddress =
             (*UpdateSection)->sh_addr + Rela.r_offset;
@@ -251,8 +478,8 @@ private:
         LLVM_DEBUG({
           Edge GE(*Kind, FixupAddress - BlockToFix->getAddress(), *TargetSymbol,
                   Addend);
-          // TODO a mapping of KIND => type then call getRelocationTypeName4
-          printEdge(dbgs(), *BlockToFix, GE, StringRef(""));
+          printEdge(dbgs(), *BlockToFix, GE,
+                    getELFX86RelocationKindName(*Kind));
           dbgs() << "\n";
         });
         BlockToFix->addEdge(*Kind, FixupAddress - BlockToFix->getAddress(),
@@ -284,25 +511,31 @@ private:
       auto StrTabSec = Obj.getSection(SecRef.sh_link);
       if (!StrTabSec)
         return StrTabSec.takeError();
-      auto StringTable = Obj.getStringTable(*StrTabSec);
+      auto StringTable = Obj.getStringTable(**StrTabSec);
       if (!StringTable)
         return StringTable.takeError();
-      auto Name = Obj.getSectionName(&SecRef);
+      auto Name = Obj.getSectionName(SecRef);
       if (!Name)
         return Name.takeError();
+
+      LLVM_DEBUG(dbgs() << "Processing symbol section " << *Name << ":\n");
+
       auto Section = G->findSectionByName(*Name);
       if (!Section)
-        return make_error<llvm::StringError>("Could not find a section",
+        return make_error<llvm::StringError>("Could not find a section " +
+                                             *Name,
                                              llvm::inconvertibleErrorCode());
       // we only have one for now
       auto blocks = Section->blocks();
       if (blocks.empty())
         return make_error<llvm::StringError>("Section has no block",
                                              llvm::inconvertibleErrorCode());
-
+      int SymbolIndex = -1;
       for (auto SymRef : *Symbols) {
+        ++SymbolIndex;
         auto Type = SymRef.getType();
-        if (Type == ELF::STT_NOTYPE || Type == ELF::STT_FILE)
+
+        if (Type == ELF::STT_FILE || SymbolIndex == 0)
           continue;
         // these should do it for now
         // if(Type != ELF::STT_NOTYPE &&
@@ -312,68 +545,119 @@ private:
         //   Type != ELF::STT_COMMON) {
         //     continue;
         //   }
-        std::pair<Linkage, Scope> bindings;
         auto Name = SymRef.getName(*StringTable);
         // I am not sure on If this is going to hold as an invariant. Revisit.
         if (!Name)
           return Name.takeError();
-        // TODO: weak and hidden
-        if (SymRef.isExternal())
-          bindings = {Linkage::Strong, Scope::Default};
-        else
-          bindings = {Linkage::Strong, Scope::Local};
+
+        if (SymRef.isCommon()) {
+          // Symbols in SHN_COMMON refer to uninitialized data. The st_value
+          // field holds alignment constraints.
+          Symbol &S =
+              G->addCommonSymbol(*Name, Scope::Default, getCommonSection(), 0,
+                                 SymRef.st_size, SymRef.getValue(), false);
+          JITSymbolTable[SymbolIndex] = &S;
+          continue;
+        }
+
+        // Map Visibility and Binding to Scope and Linkage:
+        Linkage L = Linkage::Strong;
+        Scope S = Scope::Default;
+
+        switch (SymRef.getBinding()) {
+        case ELF::STB_LOCAL:
+          S = Scope::Local;
+          break;
+        case ELF::STB_GLOBAL:
+          // Nothing to do here.
+          break;
+        case ELF::STB_WEAK:
+          L = Linkage::Weak;
+          break;
+        default:
+          return make_error<StringError>("Unrecognized symbol binding for " +
+                                             *Name,
+                                         inconvertibleErrorCode());
+        }
+
+        switch (SymRef.getVisibility()) {
+        case ELF::STV_DEFAULT:
+        case ELF::STV_PROTECTED:
+          // FIXME: Make STV_DEFAULT symbols pre-emptible? This probably needs
+          // Orc support.
+          // Otherwise nothing to do here.
+          break;
+        case ELF::STV_HIDDEN:
+          // Default scope -> Hidden scope. No effect on local scope.
+          if (S == Scope::Default)
+            S = Scope::Hidden;
+          break;
+        case ELF::STV_INTERNAL:
+          return make_error<StringError>("Unrecognized symbol visibility for " +
+                                             *Name,
+                                         inconvertibleErrorCode());
+        }
 
         if (SymRef.isDefined() &&
-            (Type == ELF::STT_FUNC || Type == ELF::STT_OBJECT)) {
+            (Type == ELF::STT_FUNC || Type == ELF::STT_OBJECT ||
+             Type == ELF::STT_SECTION)) {
 
           auto DefinedSection = Obj.getSection(SymRef.st_shndx);
           if (!DefinedSection)
             return DefinedSection.takeError();
-          auto sectName = Obj.getSectionName(*DefinedSection);
+          auto sectName = Obj.getSectionName(**DefinedSection);
           if (!sectName)
             return Name.takeError();
 
+          // Skip debug section symbols.
+          if (isDwarfSection(*sectName))
+            continue;
+
           auto JitSection = G->findSectionByName(*sectName);
           if (!JitSection)
             return make_error<llvm::StringError>(
-                "Could not find a section", llvm::inconvertibleErrorCode());
+                "Could not find the JitSection " + *sectName,
+                llvm::inconvertibleErrorCode());
           auto bs = JitSection->blocks();
           if (bs.empty())
             return make_error<llvm::StringError>(
                 "Section has no block", llvm::inconvertibleErrorCode());
 
-          auto B = *bs.begin();
-          LLVM_DEBUG({ dbgs() << "  " << *Name << ": "; });
+          auto *B = *bs.begin();
+          LLVM_DEBUG({ dbgs() << "  " << *Name << " at index " << SymbolIndex << "\n"; });
+          if (SymRef.getType() == ELF::STT_SECTION)
+            *Name = *sectName;
+          auto &Sym = G->addDefinedSymbol(
+              *B, SymRef.getValue(), *Name, SymRef.st_size, L, S,
+              SymRef.getType() == ELF::STT_FUNC, false);
+          JITSymbolTable[SymbolIndex] = &Sym;
+        } else if (SymRef.isUndefined() && SymRef.isExternal()) {
+          auto &Sym = G->addExternalSymbol(*Name, SymRef.st_size, L);
+          JITSymbolTable[SymbolIndex] = &Sym;
+        } else
+          LLVM_DEBUG({
+              dbgs()
+                << "Not creating graph symbol for normalized symbol at index "
+                << SymbolIndex << ", \"" << *Name << "\"\n";
+            });
 
-          auto &S = G->addDefinedSymbol(
-              *B, SymRef.getValue(), *Name, SymRef.st_size, bindings.first,
-              bindings.second, SymRef.getType() == ELF::STT_FUNC, false);
-          JITSymbolTable[SymRef.st_shndx] = &S;
-        }
-        //TODO: The following has to be implmented.
+        // TODO: The following has to be implmented.
         // leaving commented out to save time for future patchs
         /*
           G->addAbsoluteSymbol(*Name, SymRef.getValue(), SymRef.st_size,
           Linkage::Strong, Scope::Default, false);
-
-          if(SymRef.isCommon()) {
-            G->addCommonSymbol(*Name, Scope::Default, getCommonSection(), 0, 0,
-          SymRef.getValue(), false);
-          }
-
-
-          //G->addExternalSymbol(*Name, SymRef.st_size, Linkage::Strong);
-  */
+        */
       }
     }
     return Error::success();
   }
 
 public:
-  ELFLinkGraphBuilder_x86_64(std::string filename,
+  ELFLinkGraphBuilder_x86_64(StringRef FileName,
                              const object::ELFFile<object::ELF64LE> &Obj)
-      : G(std::make_unique<LinkGraph>(filename, getPointerSize(Obj),
-                                      getEndianness(Obj))),
+      : G(std::make_unique<LinkGraph>(FileName.str(),
+                                      Triple("x86_64-unknown-linux"),
+                                      getPointerSize(Obj), getEndianness(Obj))),
         Obj(Obj) {}
 
   Expected<std::unique_ptr<LinkGraph>> buildGraph() {
@@ -409,55 +693,121 @@ class ELFJITLinker_x86_64 : public JITLinker<ELFJITLinker_x86_64> {
 
 public:
   ELFJITLinker_x86_64(std::unique_ptr<JITLinkContext> Ctx,
+                      std::unique_ptr<LinkGraph> G,
                       PassConfiguration PassConfig)
-      : JITLinker(std::move(Ctx), std::move(PassConfig)) {}
+      : JITLinker(std::move(Ctx), std::move(G), std::move(PassConfig)) {}
 
 private:
-  StringRef getEdgeKindName(Edge::Kind R) const override { return StringRef(); }
-
-  Expected<std::unique_ptr<LinkGraph>>
-  buildGraph(MemoryBufferRef ObjBuffer) override {
-    auto ELFObj = object::ObjectFile::createELFObjectFile(ObjBuffer);
-    if (!ELFObj)
-      return ELFObj.takeError();
+  StringRef getEdgeKindName(Edge::Kind R) const override {
+    return getELFX86RelocationKindName(R);
+  }
 
-    auto &ELFObjFile = cast<object::ELFObjectFile<object::ELF64LE>>(**ELFObj);
-    std::string fileName(ELFObj->get()->getFileName());
-    return ELFLinkGraphBuilder_x86_64(std::move(fileName),
-                                      *ELFObjFile.getELFFile())
-        .buildGraph();
+  static Error targetOutOfRangeError(const Block &B, const Edge &E) {
+    std::string ErrMsg;
+    {
+      raw_string_ostream ErrStream(ErrMsg);
+      ErrStream << "Relocation target out of range: ";
+      printEdge(ErrStream, B, E, getELFX86RelocationKindName(E.getKind()));
+      ErrStream << "\n";
+    }
+    return make_error<JITLinkError>(std::move(ErrMsg));
   }
 
   Error applyFixup(Block &B, const Edge &E, char *BlockWorkingMem) const {
     using namespace ELF_x86_64_Edges;
+    using namespace llvm::support;
     char *FixupPtr = BlockWorkingMem + E.getOffset();
     JITTargetAddress FixupAddress = B.getAddress() + E.getOffset();
     switch (E.getKind()) {
-
+    case ELFX86RelocationKind::Branch32:
+    case ELFX86RelocationKind::Branch32ToStub:
     case ELFX86RelocationKind::PCRel32:
+    case ELFX86RelocationKind::PCRel32GOTLoad: {
+      int64_t Value = E.getTarget().getAddress() + E.getAddend() - FixupAddress;
+      if (Value < std::numeric_limits<int32_t>::min() ||
+          Value > std::numeric_limits<int32_t>::max())
+        return targetOutOfRangeError(B, E);
+      *(little32_t *)FixupPtr = Value;
+      break;
+    }
+    case ELFX86RelocationKind::Pointer64: {
+      int64_t Value = E.getTarget().getAddress() + E.getAddend();
+      *(ulittle64_t *)FixupPtr = Value;
+      break;
+    }
+    case ELFX86RelocationKind::Delta64: {
       int64_t Value = E.getTarget().getAddress() + E.getAddend() - FixupAddress;
-      // verify
-      *(support::little32_t *)FixupPtr = Value;
+      *(little64_t *)FixupPtr = Value;
       break;
     }
+    }
     return Error::success();
   }
 };
 
-void jitLink_ELF_x86_64(std::unique_ptr<JITLinkContext> Ctx) {
+Expected<std::unique_ptr<LinkGraph>>
+createLinkGraphFromELFObject_x86_64(MemoryBufferRef ObjectBuffer) {
+  LLVM_DEBUG({
+    dbgs() << "Building jitlink graph for new input "
+           << ObjectBuffer.getBufferIdentifier() << "...\n";
+  });
+
+  auto ELFObj = object::ObjectFile::createELFObjectFile(ObjectBuffer);
+  if (!ELFObj)
+    return ELFObj.takeError();
+
+  auto &ELFObjFile = cast<object::ELFObjectFile<object::ELF64LE>>(**ELFObj);
+  return ELFLinkGraphBuilder_x86_64((*ELFObj)->getFileName(),
+                                    ELFObjFile.getELFFile())
+      .buildGraph();
+}
+
+void link_ELF_x86_64(std::unique_ptr<LinkGraph> G,
+                     std::unique_ptr<JITLinkContext> Ctx) {
   PassConfiguration Config;
-  Triple TT("x86_64-linux");
-  // Construct a JITLinker and run the link function.
-  // Add a mark-live pass.
-  if (auto MarkLive = Ctx->getMarkLivePass(TT))
-    Config.PrePrunePasses.push_back(std::move(MarkLive));
-  else
-    Config.PrePrunePasses.push_back(markAllSymbolsLive);
 
-  if (auto Err = Ctx->modifyPassConfig(TT, Config))
+  if (Ctx->shouldAddDefaultTargetPasses(G->getTargetTriple())) {
+
+    Config.PrePrunePasses.push_back(EHFrameSplitter(".eh_frame"));
+    Config.PrePrunePasses.push_back(EHFrameEdgeFixer(
+        ".eh_frame", G->getPointerSize(), Delta64, Delta32, NegDelta32));
+
+    // Construct a JITLinker and run the link function.
+    // Add a mark-live pass.
+    if (auto MarkLive = Ctx->getMarkLivePass(G->getTargetTriple()))
+      Config.PrePrunePasses.push_back(std::move(MarkLive));
+    else
+      Config.PrePrunePasses.push_back(markAllSymbolsLive);
+
+    // Add an in-place GOT/Stubs pass.
+    Config.PostPrunePasses.push_back([](LinkGraph &G) -> Error {
+      ELF_x86_64_GOTAndStubsBuilder(G).run();
+      return Error::success();
+    });
+
+    // Add GOT/Stubs optimizer pass.
+    Config.PreFixupPasses.push_back(optimizeELF_x86_64_GOTAndStubs);
+  }
+
+  if (auto Err = Ctx->modifyPassConfig(G->getTargetTriple(), Config))
     return Ctx->notifyFailed(std::move(Err));
 
-  ELFJITLinker_x86_64::link(std::move(Ctx), std::move(Config));
+  ELFJITLinker_x86_64::link(std::move(Ctx), std::move(G), std::move(Config));
+}
+StringRef getELFX86RelocationKindName(Edge::Kind R) {
+  switch (R) {
+  case PCRel32:
+    return "PCRel32";
+  case Pointer64:
+    return "Pointer64";
+  case PCRel32GOTLoad:
+    return "PCRel32GOTLoad";
+  case Branch32:
+    return "Branch32";
+  case Branch32ToStub:
+    return "Branch32ToStub";
+  }
+  return getGenericEdgeKindName(static_cast<Edge::Kind>(R));
 }
 } // end namespace jitlink
 } // end namespace llvm
diff --git a/llvm/lib/ExecutionEngine/JITLink/JITLink.cpp b/llvm/lib/ExecutionEngine/JITLink/JITLink.cpp
index 5105ec495148..93dfba9c759b 100644
--- a/llvm/lib/ExecutionEngine/JITLink/JITLink.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/JITLink.cpp
@@ -64,7 +64,7 @@ const char *getGenericEdgeKindName(Edge::Kind K) {
   case Edge::KeepAlive:
     return "Keep-Alive";
   default:
-    llvm_unreachable("Unrecognized relocation kind");
+    return "<Unrecognized edge kind>";
   }
 }
 
@@ -93,6 +93,7 @@ const char *getScopeName(Scope S) {
 raw_ostream &operator<<(raw_ostream &OS, const Block &B) {
   return OS << formatv("{0:x16}", B.getAddress()) << " -- "
             << formatv("{0:x16}", B.getAddress() + B.getSize()) << ": "
+            << "size = " << formatv("{0:x}", B.getSize()) << ", "
             << (B.isZeroFill() ? "zero-fill" : "content")
             << ", align = " << B.getAlignment()
             << ", align-ofs = " << B.getAlignmentOffset()
@@ -126,10 +127,10 @@ raw_ostream &operator<<(raw_ostream &OS, const Symbol &Sym) {
     break;
   }
   OS << (Sym.isLive() ? '+' : '-')
-     << ", size = " << formatv("{0:x8}", Sym.getSize())
+     << ", size = " << formatv("{0:x}", Sym.getSize())
      << ", addr = " << formatv("{0:x16}", Sym.getAddress()) << " ("
      << formatv("{0:x16}", Sym.getAddressable().getAddress()) << " + "
-     << formatv("{0:x8}", Sym.getOffset());
+     << formatv("{0:x}", Sym.getOffset());
   if (Sym.isDefined())
     OS << " " << Sym.getBlock().getSection().getName();
   OS << ")>";
@@ -139,8 +140,33 @@ raw_ostream &operator<<(raw_ostream &OS, const Symbol &Sym) {
 void printEdge(raw_ostream &OS, const Block &B, const Edge &E,
                StringRef EdgeKindName) {
   OS << "edge@" << formatv("{0:x16}", B.getAddress() + E.getOffset()) << ": "
-     << formatv("{0:x16}", B.getAddress()) << " + " << E.getOffset() << " -- "
-     << EdgeKindName << " -> " << E.getTarget() << " + " << E.getAddend();
+     << formatv("{0:x16}", B.getAddress()) << " + "
+     << formatv("{0:x}", E.getOffset()) << " -- " << EdgeKindName << " -> ";
+
+  auto &TargetSym = E.getTarget();
+  if (TargetSym.hasName())
+    OS << TargetSym.getName();
+  else {
+    auto &TargetBlock = TargetSym.getBlock();
+    auto &TargetSec = TargetBlock.getSection();
+    JITTargetAddress SecAddress = ~JITTargetAddress(0);
+    for (auto *B : TargetSec.blocks())
+      if (B->getAddress() < SecAddress)
+        SecAddress = B->getAddress();
+
+    JITTargetAddress SecDelta = TargetSym.getAddress() - SecAddress;
+    OS << formatv("{0:x16}", TargetSym.getAddress()) << " (section "
+       << TargetSec.getName();
+    if (SecDelta)
+      OS << " + " << formatv("{0:x}", SecDelta);
+    OS << " / block " << formatv("{0:x16}", TargetBlock.getAddress());
+    if (TargetSym.getOffset())
+      OS << " + " << formatv("{0:x}", TargetSym.getOffset());
+    OS << ")";
+  }
+
+  if (E.getAddend() != 0)
+    OS << " + " << E.getAddend();
 }
 
 Section::~Section() {
@@ -296,15 +322,27 @@ Error markAllSymbolsLive(LinkGraph &G) {
   return Error::success();
 }
 
-void jitLink(std::unique_ptr<JITLinkContext> Ctx) {
-  auto Magic = identify_magic(Ctx->getObjectBuffer().getBuffer());
+Expected<std::unique_ptr<LinkGraph>>
+createLinkGraphFromObject(MemoryBufferRef ObjectBuffer) {
+  auto Magic = identify_magic(ObjectBuffer.getBuffer());
   switch (Magic) {
   case file_magic::macho_object:
-    return jitLink_MachO(std::move(Ctx));
+    return createLinkGraphFromMachOObject(std::move(ObjectBuffer));
   case file_magic::elf_relocatable:
-    return jitLink_ELF(std::move(Ctx));
+    return createLinkGraphFromELFObject(std::move(ObjectBuffer));
+  default:
+    return make_error<JITLinkError>("Unsupported file format");
+  };
+}
+
+void link(std::unique_ptr<LinkGraph> G, std::unique_ptr<JITLinkContext> Ctx) {
+  switch (G->getTargetTriple().getObjectFormat()) {
+  case Triple::MachO:
+    return link_MachO(std::move(G), std::move(Ctx));
+  case Triple::ELF:
+    return link_ELF(std::move(G), std::move(Ctx));
   default:
-    Ctx->notifyFailed(make_error<JITLinkError>("Unsupported file format"));
+    Ctx->notifyFailed(make_error<JITLinkError>("Unsupported object format"));
   };
 }
 
diff --git a/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.cpp b/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.cpp
index 1d76a49939dc..7a5e014f223d 100644
--- a/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.cpp
@@ -24,15 +24,6 @@ JITLinkerBase::~JITLinkerBase() {}
 
 void JITLinkerBase::linkPhase1(std::unique_ptr<JITLinkerBase> Self) {
 
-  LLVM_DEBUG({ dbgs() << "Building jitlink graph for new input...\n"; });
-
-  // Build the link graph.
-  if (auto GraphOrErr = buildGraph(Ctx->getObjectBuffer()))
-    G = std::move(*GraphOrErr);
-  else
-    return Ctx->notifyFailed(GraphOrErr.takeError());
-  assert(G && "Graph should have been created by buildGraph above");
-
   LLVM_DEBUG({
     dbgs() << "Starting link phase 1 for graph " << G->getName() << "\n";
   });
@@ -64,10 +55,22 @@ void JITLinkerBase::linkPhase1(std::unique_ptr<JITLinkerBase> Self) {
   if (auto Err = allocateSegments(Layout))
     return Ctx->notifyFailed(std::move(Err));
 
+  LLVM_DEBUG({
+    dbgs() << "Link graph \"" << G->getName()
+           << "\" before post-allocation passes:\n";
+    dumpGraph(dbgs());
+  });
+
+  // Run post-allocation passes.
+  if (auto Err = runPasses(Passes.PostAllocationPasses))
+    return Ctx->notifyFailed(std::move(Err));
+
   // Notify client that the defined symbols have been assigned addresses.
   LLVM_DEBUG(
       { dbgs() << "Resolving symbols defined in " << G->getName() << "\n"; });
-  Ctx->notifyResolved(*G);
+
+  if (auto Err = Ctx->notifyResolved(*G))
+    return Ctx->notifyFailed(std::move(Err));
 
   auto ExternalSymbols = getExternalSymbolNames();
 
@@ -117,11 +120,11 @@ void JITLinkerBase::linkPhase2(std::unique_ptr<JITLinkerBase> Self,
 
   LLVM_DEBUG({
     dbgs() << "Link graph \"" << G->getName()
-           << "\" before post-allocation passes:\n";
+           << "\" before pre-fixup passes:\n";
     dumpGraph(dbgs());
   });
 
-  if (auto Err = runPasses(Passes.PostAllocationPasses))
+  if (auto Err = runPasses(Passes.PreFixupPasses))
     return deallocateAndBailOut(std::move(Err));
 
   LLVM_DEBUG({
@@ -261,7 +264,8 @@ Error JITLinkerBase::allocateSegments(const SegmentLayoutMap &Layout) {
   }
   LLVM_DEBUG(dbgs() << " }\n");
 
-  if (auto AllocOrErr = Ctx->getMemoryManager().allocate(Segments))
+  if (auto AllocOrErr =
+          Ctx->getMemoryManager().allocate(Ctx->getJITLinkDylib(), Segments))
     Alloc = std::move(*AllocOrErr);
   else
     return AllocOrErr.takeError();
@@ -332,12 +336,6 @@ void JITLinkerBase::applyLookupResult(AsyncLookupResult Result) {
       dbgs() << "  " << Sym->getName() << ": "
              << formatv("{0:x16}", Sym->getAddress()) << "\n";
   });
-  assert(llvm::all_of(G->external_symbols(),
-                      [](Symbol *Sym) {
-                        return Sym->getAddress() != 0 ||
-                               Sym->getLinkage() == Linkage::Weak;
-                      }) &&
-         "All strong external symbols should have been resolved by now");
 }
 
 void JITLinkerBase::copyBlockContentToWorkingMemory(
@@ -445,16 +443,19 @@ void prune(LinkGraph &G) {
     VisitedBlocks.insert(&B);
 
     for (auto &E : Sym->getBlock().edges()) {
-      if (E.getTarget().isDefined() && !E.getTarget().isLive()) {
-        E.getTarget().setLive(true);
+      // If the edge target is a defined symbol that is being newly marked live
+      // then add it to the worklist.
+      if (E.getTarget().isDefined() && !E.getTarget().isLive())
         Worklist.push_back(&E.getTarget());
-      }
+
+      // Mark the target live.
+      E.getTarget().setLive(true);
     }
   }
 
-  // Collect all the symbols to remove, then remove them.
+  // Collect all defined symbols to remove, then remove them.
   {
-    LLVM_DEBUG(dbgs() << "Dead-stripping symbols:\n");
+    LLVM_DEBUG(dbgs() << "Dead-stripping defined symbols:\n");
     std::vector<Symbol *> SymbolsToRemove;
     for (auto *Sym : G.defined_symbols())
       if (!Sym->isLive())
@@ -477,6 +478,19 @@ void prune(LinkGraph &G) {
       G.removeBlock(*B);
     }
   }
+
+  // Collect all external symbols to remove, then remove them.
+  {
+    LLVM_DEBUG(dbgs() << "Removing unused external symbols:\n");
+    std::vector<Symbol *> SymbolsToRemove;
+    for (auto *Sym : G.external_symbols())
+      if (!Sym->isLive())
+        SymbolsToRemove.push_back(Sym);
+    for (auto *Sym : SymbolsToRemove) {
+      LLVM_DEBUG(dbgs() << "  " << *Sym << "...\n");
+      G.removeExternalSymbol(*Sym);
+    }
+  }
 }
 
 } // end namespace jitlink
diff --git a/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.h b/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.h
index 87e5e8bbc98d..1d28f5006b2b 100644
--- a/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.h
+++ b/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.h
@@ -32,9 +32,11 @@ namespace jitlink {
 /// remaining linker work) to allow them to be performed asynchronously.
 class JITLinkerBase {
 public:
-  JITLinkerBase(std::unique_ptr<JITLinkContext> Ctx, PassConfiguration Passes)
-      : Ctx(std::move(Ctx)), Passes(std::move(Passes)) {
+  JITLinkerBase(std::unique_ptr<JITLinkContext> Ctx,
+                std::unique_ptr<LinkGraph> G, PassConfiguration Passes)
+      : Ctx(std::move(Ctx)), G(std::move(G)), Passes(std::move(Passes)) {
     assert(this->Ctx && "Ctx can not be null");
+    assert(this->G && "G can not be null");
   }
 
   virtual ~JITLinkerBase();
@@ -50,8 +52,7 @@ protected:
   using SegmentLayoutMap = DenseMap<unsigned, SegmentLayout>;
 
   // Phase 1:
-  //   1.1: Build link graph
-  //   1.2: Run pre-prune passes
+  //   1.1: Run pre-prune passes
   //   1.2: Prune graph
   //   1.3: Run post-prune passes
   //   1.4: Sort blocks into segments
@@ -72,11 +73,6 @@ protected:
   //   3.1: Call OnFinalized callback, handing off allocation.
   void linkPhase3(std::unique_ptr<JITLinkerBase> Self, Error Err);
 
-  // Build a graph from the given object buffer.
-  // To be implemented by the client.
-  virtual Expected<std::unique_ptr<LinkGraph>>
-  buildGraph(MemoryBufferRef ObjBuffer) = 0;
-
   // For debug dumping of the link graph.
   virtual StringRef getEdgeKindName(Edge::Kind K) const = 0;
 
@@ -113,8 +109,8 @@ private:
   void dumpGraph(raw_ostream &OS);
 
   std::unique_ptr<JITLinkContext> Ctx;
-  PassConfiguration Passes;
   std::unique_ptr<LinkGraph> G;
+  PassConfiguration Passes;
   std::unique_ptr<JITLinkMemoryManager::Allocation> Alloc;
 };
 
diff --git a/llvm/lib/ExecutionEngine/JITLink/JITLinkMemoryManager.cpp b/llvm/lib/ExecutionEngine/JITLink/JITLinkMemoryManager.cpp
index 68ec9d79af9b..fbbb29e9164a 100644
--- a/llvm/lib/ExecutionEngine/JITLink/JITLinkMemoryManager.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/JITLinkMemoryManager.cpp
@@ -17,7 +17,8 @@ JITLinkMemoryManager::~JITLinkMemoryManager() = default;
 JITLinkMemoryManager::Allocation::~Allocation() = default;
 
 Expected<std::unique_ptr<JITLinkMemoryManager::Allocation>>
-InProcessMemoryManager::allocate(const SegmentsRequestMap &Request) {
+InProcessMemoryManager::allocate(const JITLinkDylib *JD,
+                                 const SegmentsRequestMap &Request) {
 
   using AllocationMap = DenseMap<unsigned, sys::MemoryBlock>;
 
diff --git a/llvm/lib/ExecutionEngine/JITLink/MachO.cpp b/llvm/lib/ExecutionEngine/JITLink/MachO.cpp
index b3e45868ab22..e9327df6da41 100644
--- a/llvm/lib/ExecutionEngine/JITLink/MachO.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/MachO.cpp
@@ -27,39 +27,29 @@ using namespace llvm;
 namespace llvm {
 namespace jitlink {
 
-void jitLink_MachO(std::unique_ptr<JITLinkContext> Ctx) {
-
-  // We don't want to do full MachO validation here. Just parse enough of the
-  // header to find out what MachO linker to use.
-
-  StringRef Data = Ctx->getObjectBuffer().getBuffer();
-  if (Data.size() < 4) {
-    StringRef BufferName = Ctx->getObjectBuffer().getBufferIdentifier();
-    Ctx->notifyFailed(make_error<JITLinkError>("Truncated MachO buffer \"" +
-                                               BufferName + "\""));
-    return;
-  }
+Expected<std::unique_ptr<LinkGraph>>
+createLinkGraphFromMachOObject(MemoryBufferRef ObjectBuffer) {
+  StringRef Data = ObjectBuffer.getBuffer();
+  if (Data.size() < 4)
+    return make_error<JITLinkError>("Truncated MachO buffer \"" +
+                                    ObjectBuffer.getBufferIdentifier() + "\"");
 
   uint32_t Magic;
   memcpy(&Magic, Data.data(), sizeof(uint32_t));
   LLVM_DEBUG({
     dbgs() << "jitLink_MachO: magic = " << format("0x%08" PRIx32, Magic)
-           << ", identifier = \""
-           << Ctx->getObjectBuffer().getBufferIdentifier() << "\"\n";
+           << ", identifier = \"" << ObjectBuffer.getBufferIdentifier()
+           << "\"\n";
   });
 
-  if (Magic == MachO::MH_MAGIC || Magic == MachO::MH_CIGAM) {
-    Ctx->notifyFailed(
-        make_error<JITLinkError>("MachO 32-bit platforms not supported"));
-    return;
-  } else if (Magic == MachO::MH_MAGIC_64 || Magic == MachO::MH_CIGAM_64) {
+  if (Magic == MachO::MH_MAGIC || Magic == MachO::MH_CIGAM)
+    return make_error<JITLinkError>("MachO 32-bit platforms not supported");
+  else if (Magic == MachO::MH_MAGIC_64 || Magic == MachO::MH_CIGAM_64) {
 
-    if (Data.size() < sizeof(MachO::mach_header_64)) {
-      StringRef BufferName = Ctx->getObjectBuffer().getBufferIdentifier();
-      Ctx->notifyFailed(make_error<JITLinkError>("Truncated MachO buffer \"" +
-                                                 BufferName + "\""));
-      return;
-    }
+    if (Data.size() < sizeof(MachO::mach_header_64))
+      return make_error<JITLinkError>("Truncated MachO buffer \"" +
+                                      ObjectBuffer.getBufferIdentifier() +
+                                      "\"");
 
     // Read the CPU type from the header.
     uint32_t CPUType;
@@ -74,15 +64,27 @@ void jitLink_MachO(std::unique_ptr<JITLinkContext> Ctx) {
 
     switch (CPUType) {
     case MachO::CPU_TYPE_ARM64:
-      return jitLink_MachO_arm64(std::move(Ctx));
+      return createLinkGraphFromMachOObject_arm64(std::move(ObjectBuffer));
     case MachO::CPU_TYPE_X86_64:
-      return jitLink_MachO_x86_64(std::move(Ctx));
+      return createLinkGraphFromMachOObject_x86_64(std::move(ObjectBuffer));
     }
+    return make_error<JITLinkError>("MachO-64 CPU type not valid");
+  } else
+    return make_error<JITLinkError>("Unrecognized MachO magic value");
+}
+
+void link_MachO(std::unique_ptr<LinkGraph> G,
+                std::unique_ptr<JITLinkContext> Ctx) {
+
+  switch (G->getTargetTriple().getArch()) {
+  case Triple::aarch64:
+    return link_MachO_arm64(std::move(G), std::move(Ctx));
+  case Triple::x86_64:
+    return link_MachO_x86_64(std::move(G), std::move(Ctx));
+  default:
     Ctx->notifyFailed(make_error<JITLinkError>("MachO-64 CPU type not valid"));
     return;
   }
-
-  Ctx->notifyFailed(make_error<JITLinkError>("MachO magic not valid"));
 }
 
 } // end namespace jitlink
diff --git a/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp b/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp
index fa3f403b717c..4602154eb579 100644
--- a/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp
@@ -45,10 +45,12 @@ Expected<std::unique_ptr<LinkGraph>> MachOLinkGraphBuilder::buildGraph() {
   return std::move(G);
 }
 
-MachOLinkGraphBuilder::MachOLinkGraphBuilder(const object::MachOObjectFile &Obj)
+MachOLinkGraphBuilder::MachOLinkGraphBuilder(const object::MachOObjectFile &Obj,
+                                             Triple TT)
     : Obj(Obj),
       G(std::make_unique<LinkGraph>(std::string(Obj.getFileName()),
-                                    getPointerSize(Obj), getEndianness(Obj))) {}
+                                    std::move(TT), getPointerSize(Obj),
+                                    getEndianness(Obj))) {}
 
 void MachOLinkGraphBuilder::addCustomSectionParser(
     StringRef SectionName, SectionParserFunction Parser) {
@@ -64,10 +66,8 @@ Linkage MachOLinkGraphBuilder::getLinkage(uint16_t Desc) {
 }
 
 Scope MachOLinkGraphBuilder::getScope(StringRef Name, uint8_t Type) {
-  if (Type & MachO::N_PEXT)
-    return Scope::Hidden;
   if (Type & MachO::N_EXT) {
-    if (Name.startswith("l"))
+    if ((Type & MachO::N_PEXT) || Name.startswith("l"))
       return Scope::Hidden;
     else
       return Scope::Default;
diff --git a/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.h b/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.h
index dd3bcf27494c..26e6859de91d 100644
--- a/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.h
+++ b/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.h
@@ -16,10 +16,10 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ExecutionEngine/JITLink/JITLink.h"
+#include "llvm/Object/MachO.h"
 
 #include "EHFrameSupportImpl.h"
 #include "JITLinkGeneric.h"
-#include "llvm/Object/MachO.h"
 
 #include <list>
 
@@ -81,7 +81,7 @@ protected:
 
   using SectionParserFunction = std::function<Error(NormalizedSection &S)>;
 
-  MachOLinkGraphBuilder(const object::MachOObjectFile &Obj);
+  MachOLinkGraphBuilder(const object::MachOObjectFile &Obj, Triple TT);
 
   LinkGraph &getGraph() const { return *G; }
 
diff --git a/llvm/lib/ExecutionEngine/JITLink/MachO_arm64.cpp b/llvm/lib/ExecutionEngine/JITLink/MachO_arm64.cpp
index 463845a5b8cb..8366e9658539 100644
--- a/llvm/lib/ExecutionEngine/JITLink/MachO_arm64.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/MachO_arm64.cpp
@@ -26,7 +26,7 @@ namespace {
 class MachOLinkGraphBuilder_arm64 : public MachOLinkGraphBuilder {
 public:
   MachOLinkGraphBuilder_arm64(const object::MachOObjectFile &Obj)
-      : MachOLinkGraphBuilder(Obj),
+      : MachOLinkGraphBuilder(Obj, Triple("arm64-apple-darwin")),
         NumSymbols(Obj.getSymtabLoadCommand().nsyms) {}
 
 private:
@@ -148,10 +148,11 @@ private:
       else
         return ToSymbolOrErr.takeError();
     } else {
-      if (auto ToSymbolOrErr = findSymbolByAddress(FixupValue))
-        ToSymbol = &*ToSymbolOrErr;
-      else
-        return ToSymbolOrErr.takeError();
+      auto ToSymbolSec = findSectionByIndex(UnsignedRI.r_symbolnum - 1);
+      if (!ToSymbolSec)
+        return ToSymbolSec.takeError();
+      ToSymbol = getSymbolByAddress(ToSymbolSec->Address);
+      assert(ToSymbol && "No symbol for section");
       FixupValue -= ToSymbol->getAddress();
     }
 
@@ -181,6 +182,8 @@ private:
     using namespace support;
     auto &Obj = getObject();
 
+    LLVM_DEBUG(dbgs() << "Processing relocations:\n");
+
     for (auto &S : Obj.sections()) {
 
       JITTargetAddress SectionAddress = S.getAddress();
@@ -199,8 +202,8 @@ private:
             getSectionByIndex(Obj.getSectionIndex(S.getRawDataRefImpl()));
         if (!NSec.GraphSection) {
           LLVM_DEBUG({
-            dbgs() << "Skipping relocations for MachO section " << NSec.SegName
-                   << "/" << NSec.SectName
+            dbgs() << "  Skipping relocations for MachO section "
+                   << NSec.SegName << "/" << NSec.SectName
                    << " which has no associated graph section\n";
           });
           continue;
@@ -221,9 +224,10 @@ private:
         JITTargetAddress FixupAddress = SectionAddress + (uint32_t)RI.r_address;
 
         LLVM_DEBUG({
-          dbgs() << "Processing " << getMachOARM64RelocationKindName(*Kind)
-                 << " relocation at " << format("0x%016" PRIx64, FixupAddress)
-                 << "\n";
+          auto &NSec =
+              getSectionByIndex(Obj.getSectionIndex(S.getRawDataRefImpl()));
+          dbgs() << "  " << NSec.SectName << " + "
+                 << formatv("{0:x8}", RI.r_address) << ":\n";
         });
 
         // Find the block that the fixup points to.
@@ -252,7 +256,7 @@ private:
           // If this is an Addend relocation then process it and move to the
           // paired reloc.
 
-          Addend = RI.r_symbolnum;
+          Addend = SignExtend64(RI.r_symbolnum, 24);
 
           if (RelItr == RelEnd)
             return make_error<JITLinkError>("Unpaired Addend reloc at " +
@@ -268,11 +272,12 @@ private:
             return make_error<JITLinkError>(
                 "Invalid relocation pair: Addend + " +
                 getMachOARM64RelocationKindName(*Kind));
-          else
-            LLVM_DEBUG({
-              dbgs() << "  pair is " << getMachOARM64RelocationKindName(*Kind)
-                     << "`\n";
-            });
+
+          LLVM_DEBUG({
+            dbgs() << "    Addend: value = " << formatv("{0:x6}", Addend)
+                   << ", pair is " << getMachOARM64RelocationKindName(*Kind)
+                   << "\n";
+          });
 
           // Find the address of the value to fix up.
           JITTargetAddress PairedFixupAddress =
@@ -335,6 +340,11 @@ private:
             TargetSymbol = TargetSymbolOrErr->GraphSymbol;
           else
             return TargetSymbolOrErr.takeError();
+          uint32_t Instr = *(const ulittle32_t *)FixupContent;
+          uint32_t EncodedAddend = (Instr & 0x003FFC00) >> 10;
+          if (EncodedAddend != 0)
+            return make_error<JITLinkError>("GOTPAGEOFF12 target has non-zero "
+                                            "encoded addend");
           break;
         }
         case GOTPageOffset12: {
@@ -377,6 +387,7 @@ private:
         }
 
         LLVM_DEBUG({
+          dbgs() << "    ";
           Edge GE(*Kind, FixupAddress - BlockToFix->getAddress(), *TargetSymbol,
                   Addend);
           printEdge(dbgs(), *BlockToFix, GE,
@@ -490,22 +501,15 @@ class MachOJITLinker_arm64 : public JITLinker<MachOJITLinker_arm64> {
 
 public:
   MachOJITLinker_arm64(std::unique_ptr<JITLinkContext> Ctx,
+                       std::unique_ptr<LinkGraph> G,
                        PassConfiguration PassConfig)
-      : JITLinker(std::move(Ctx), std::move(PassConfig)) {}
+      : JITLinker(std::move(Ctx), std::move(G), std::move(PassConfig)) {}
 
 private:
   StringRef getEdgeKindName(Edge::Kind R) const override {
     return getMachOARM64RelocationKindName(R);
   }
 
-  Expected<std::unique_ptr<LinkGraph>>
-  buildGraph(MemoryBufferRef ObjBuffer) override {
-    auto MachOObj = object::ObjectFile::createMachOObjectFile(ObjBuffer);
-    if (!MachOObj)
-      return MachOObj.takeError();
-    return MachOLinkGraphBuilder_arm64(**MachOObj).buildGraph();
-  }
-
   static Error targetOutOfRangeError(const Block &B, const Edge &E) {
     std::string ErrMsg;
     {
@@ -518,23 +522,17 @@ private:
   }
 
   static unsigned getPageOffset12Shift(uint32_t Instr) {
-    constexpr uint32_t LDRLiteralMask = 0x3ffffc00;
+    constexpr uint32_t LoadStoreImm12Mask = 0x3b000000;
+    constexpr uint32_t Vec128Mask = 0x04800000;
 
-    // Check for a GPR LDR immediate with a zero embedded literal.
-    // If found, the top two bits contain the shift.
-    if ((Instr & LDRLiteralMask) == 0x39400000)
-      return Instr >> 30;
+    if ((Instr & LoadStoreImm12Mask) == 0x39000000) {
+      uint32_t ImplicitShift = Instr >> 30;
+      if (ImplicitShift == 0)
+        if ((Instr & Vec128Mask) == Vec128Mask)
+          ImplicitShift = 4;
 
-    // Check for a Neon LDR immediate of size 64-bit or less with a zero
-    // embedded literal. If found, the top two bits contain the shift.
-    if ((Instr & LDRLiteralMask) == 0x3d400000)
-      return Instr >> 30;
-
-    // Check for a Neon LDR immediate of size 128-bit with a zero embedded
-    // literal.
-    constexpr uint32_t SizeBitsMask = 0xc0000000;
-    if ((Instr & (LDRLiteralMask | SizeBitsMask)) == 0x3dc00000)
-      return 4;
+      return ImplicitShift;
+    }
 
     return 0;
   }
@@ -581,10 +579,12 @@ private:
     }
     case Page21:
     case GOTPage21: {
-      assert(E.getAddend() == 0 && "PAGE21/GOTPAGE21 with non-zero addend");
+      assert((E.getKind() != GOTPage21 || E.getAddend() == 0) &&
+             "GOTPAGE21 with non-zero addend");
       uint64_t TargetPage =
-          E.getTarget().getAddress() & ~static_cast<uint64_t>(4096 - 1);
-      uint64_t PCPage = B.getAddress() & ~static_cast<uint64_t>(4096 - 1);
+          (E.getTarget().getAddress() + E.getAddend()) &
+            ~static_cast<uint64_t>(4096 - 1);
+      uint64_t PCPage = FixupAddress & ~static_cast<uint64_t>(4096 - 1);
 
       int64_t PageDelta = TargetPage - PCPage;
       if (PageDelta < -(1 << 30) || PageDelta > ((1 << 30) - 1))
@@ -600,8 +600,8 @@ private:
       break;
     }
     case PageOffset12: {
-      assert(E.getAddend() == 0 && "PAGEOFF12 with non-zero addend");
-      uint64_t TargetOffset = E.getTarget().getAddress() & 0xfff;
+      uint64_t TargetOffset =
+        (E.getTarget().getAddress() + E.getAddend()) & 0xfff;
 
       uint32_t RawInstr = *(ulittle32_t *)FixupPtr;
       unsigned ImmShift = getPageOffset12Shift(RawInstr);
@@ -674,13 +674,22 @@ private:
   uint64_t NullValue = 0;
 };
 
-void jitLink_MachO_arm64(std::unique_ptr<JITLinkContext> Ctx) {
+Expected<std::unique_ptr<LinkGraph>>
+createLinkGraphFromMachOObject_arm64(MemoryBufferRef ObjectBuffer) {
+  auto MachOObj = object::ObjectFile::createMachOObjectFile(ObjectBuffer);
+  if (!MachOObj)
+    return MachOObj.takeError();
+  return MachOLinkGraphBuilder_arm64(**MachOObj).buildGraph();
+}
+
+void link_MachO_arm64(std::unique_ptr<LinkGraph> G,
+                      std::unique_ptr<JITLinkContext> Ctx) {
+
   PassConfiguration Config;
-  Triple TT("arm64-apple-ios");
 
-  if (Ctx->shouldAddDefaultTargetPasses(TT)) {
+  if (Ctx->shouldAddDefaultTargetPasses(G->getTargetTriple())) {
     // Add a mark-live pass.
-    if (auto MarkLive = Ctx->getMarkLivePass(TT))
+    if (auto MarkLive = Ctx->getMarkLivePass(G->getTargetTriple()))
       Config.PrePrunePasses.push_back(std::move(MarkLive));
     else
       Config.PrePrunePasses.push_back(markAllSymbolsLive);
@@ -692,11 +701,11 @@ void jitLink_MachO_arm64(std::unique_ptr<JITLinkContext> Ctx) {
     });
   }
 
-  if (auto Err = Ctx->modifyPassConfig(TT, Config))
+  if (auto Err = Ctx->modifyPassConfig(G->getTargetTriple(), Config))
     return Ctx->notifyFailed(std::move(Err));
 
   // Construct a JITLinker and run the link function.
-  MachOJITLinker_arm64::link(std::move(Ctx), std::move(Config));
+  MachOJITLinker_arm64::link(std::move(Ctx), std::move(G), std::move(Config));
 }
 
 StringRef getMachOARM64RelocationKindName(Edge::Kind R) {
diff --git a/llvm/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp b/llvm/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp
index a91bc3b6033c..bde4a19e71ba 100644
--- a/llvm/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp
@@ -26,7 +26,7 @@ namespace {
 class MachOLinkGraphBuilder_x86_64 : public MachOLinkGraphBuilder {
 public:
   MachOLinkGraphBuilder_x86_64(const object::MachOObjectFile &Obj)
-      : MachOLinkGraphBuilder(Obj) {}
+      : MachOLinkGraphBuilder(Obj, Triple("x86_64-apple-darwin")) {}
 
 private:
   static Expected<MachOX86RelocationKind>
@@ -150,10 +150,11 @@ private:
       else
         return ToSymbolOrErr.takeError();
     } else {
-      if (auto ToSymbolOrErr = findSymbolByAddress(FixupValue))
-        ToSymbol = &*ToSymbolOrErr;
-      else
-        return ToSymbolOrErr.takeError();
+      auto ToSymbolSec = findSectionByIndex(UnsignedRI.r_symbolnum - 1);
+      if (!ToSymbolSec)
+        return ToSymbolSec.takeError();
+      ToSymbol = getSymbolByAddress(ToSymbolSec->Address);
+      assert(ToSymbol && "No symbol for section");
       FixupValue -= ToSymbol->getAddress();
     }
 
@@ -183,6 +184,8 @@ private:
     using namespace support;
     auto &Obj = getObject();
 
+    LLVM_DEBUG(dbgs() << "Processing relocations:\n");
+
     for (auto &S : Obj.sections()) {
 
       JITTargetAddress SectionAddress = S.getAddress();
@@ -201,8 +204,8 @@ private:
             getSectionByIndex(Obj.getSectionIndex(S.getRawDataRefImpl()));
         if (!NSec.GraphSection) {
           LLVM_DEBUG({
-            dbgs() << "Skipping relocations for MachO section " << NSec.SegName
-                   << "/" << NSec.SectName
+            dbgs() << "  Skipping relocations for MachO section "
+                   << NSec.SegName << "/" << NSec.SectName
                    << " which has no associated graph section\n";
           });
           continue;
@@ -224,8 +227,10 @@ private:
         JITTargetAddress FixupAddress = SectionAddress + (uint32_t)RI.r_address;
 
         LLVM_DEBUG({
-          dbgs() << "Processing relocation at "
-                 << format("0x%016" PRIx64, FixupAddress) << "\n";
+          auto &NSec =
+              getSectionByIndex(Obj.getSectionIndex(S.getRawDataRefImpl()));
+          dbgs() << "  " << NSec.SectName << " + "
+                 << formatv("{0:x8}", RI.r_address) << ":\n";
         });
 
         // Find the block that the fixup points to.
@@ -334,12 +339,16 @@ private:
           assert(TargetSymbol && "No target symbol from parsePairRelocation?");
           break;
         }
+        case PCRel32TLV:
+          return make_error<JITLinkError>(
+              "MachO TLV relocations not yet supported");
         default:
           llvm_unreachable("Special relocation kind should not appear in "
                            "mach-o file");
         }
 
         LLVM_DEBUG({
+          dbgs() << "    ";
           Edge GE(*Kind, FixupAddress - BlockToFix->getAddress(), *TargetSymbol,
                   Addend);
           printEdge(dbgs(), *BlockToFix, GE,
@@ -539,22 +548,15 @@ class MachOJITLinker_x86_64 : public JITLinker<MachOJITLinker_x86_64> {
 
 public:
   MachOJITLinker_x86_64(std::unique_ptr<JITLinkContext> Ctx,
+                        std::unique_ptr<LinkGraph> G,
                         PassConfiguration PassConfig)
-      : JITLinker(std::move(Ctx), std::move(PassConfig)) {}
+      : JITLinker(std::move(Ctx), std::move(G), std::move(PassConfig)) {}
 
 private:
   StringRef getEdgeKindName(Edge::Kind R) const override {
     return getMachOX86RelocationKindName(R);
   }
 
-  Expected<std::unique_ptr<LinkGraph>>
-  buildGraph(MemoryBufferRef ObjBuffer) override {
-    auto MachOObj = object::ObjectFile::createMachOObjectFile(ObjBuffer);
-    if (!MachOObj)
-      return MachOObj.takeError();
-    return MachOLinkGraphBuilder_x86_64(**MachOObj).buildGraph();
-  }
-
   static Error targetOutOfRangeError(const Block &B, const Edge &E) {
     std::string ErrMsg;
     {
@@ -651,18 +653,27 @@ private:
   uint64_t NullValue = 0;
 };
 
-void jitLink_MachO_x86_64(std::unique_ptr<JITLinkContext> Ctx) {
+Expected<std::unique_ptr<LinkGraph>>
+createLinkGraphFromMachOObject_x86_64(MemoryBufferRef ObjectBuffer) {
+  auto MachOObj = object::ObjectFile::createMachOObjectFile(ObjectBuffer);
+  if (!MachOObj)
+    return MachOObj.takeError();
+  return MachOLinkGraphBuilder_x86_64(**MachOObj).buildGraph();
+}
+
+void link_MachO_x86_64(std::unique_ptr<LinkGraph> G,
+                       std::unique_ptr<JITLinkContext> Ctx) {
+
   PassConfiguration Config;
-  Triple TT("x86_64-apple-macosx");
 
-  if (Ctx->shouldAddDefaultTargetPasses(TT)) {
+  if (Ctx->shouldAddDefaultTargetPasses(G->getTargetTriple())) {
     // Add eh-frame passses.
     Config.PrePrunePasses.push_back(EHFrameSplitter("__eh_frame"));
-    Config.PrePrunePasses.push_back(
-        EHFrameEdgeFixer("__eh_frame", NegDelta32, Delta64, Delta64));
+    Config.PrePrunePasses.push_back(EHFrameEdgeFixer(
+        "__eh_frame", G->getPointerSize(), Delta64, Delta32, NegDelta32));
 
     // Add a mark-live pass.
-    if (auto MarkLive = Ctx->getMarkLivePass(TT))
+    if (auto MarkLive = Ctx->getMarkLivePass(G->getTargetTriple()))
       Config.PrePrunePasses.push_back(std::move(MarkLive));
     else
       Config.PrePrunePasses.push_back(markAllSymbolsLive);
@@ -674,14 +685,14 @@ void jitLink_MachO_x86_64(std::unique_ptr<JITLinkContext> Ctx) {
     });
 
     // Add GOT/Stubs optimizer pass.
-    Config.PostAllocationPasses.push_back(optimizeMachO_x86_64_GOTAndStubs);
+    Config.PreFixupPasses.push_back(optimizeMachO_x86_64_GOTAndStubs);
   }
 
-  if (auto Err = Ctx->modifyPassConfig(TT, Config))
+  if (auto Err = Ctx->modifyPassConfig(G->getTargetTriple(), Config))
     return Ctx->notifyFailed(std::move(Err));
 
   // Construct a JITLinker and run the link function.
-  MachOJITLinker_x86_64::link(std::move(Ctx), std::move(Config));
+  MachOJITLinker_x86_64::link(std::move(Ctx), std::move(G), std::move(Config));
 }
 
 StringRef getMachOX86RelocationKindName(Edge::Kind R) {
diff --git a/llvm/lib/ExecutionEngine/MCJIT/MCJIT.h b/llvm/lib/ExecutionEngine/MCJIT/MCJIT.h
index 83b64b5171c0..52e7eda90310 100644
--- a/llvm/lib/ExecutionEngine/MCJIT/MCJIT.h
+++ b/llvm/lib/ExecutionEngine/MCJIT/MCJIT.h
@@ -102,22 +102,22 @@ class MCJIT : public ExecutionEngine {
     }
 
     bool hasModuleBeenAddedButNotLoaded(Module *M) {
-      return AddedModules.count(M) != 0;
+      return AddedModules.contains(M);
     }
 
     bool hasModuleBeenLoaded(Module *M) {
       // If the module is in either the "loaded" or "finalized" sections it
       // has been loaded.
-      return (LoadedModules.count(M) != 0 ) || (FinalizedModules.count(M) != 0);
+      return LoadedModules.contains(M) || FinalizedModules.contains(M);
     }
 
     bool hasModuleBeenFinalized(Module *M) {
-      return FinalizedModules.count(M) != 0;
+      return FinalizedModules.contains(M);
     }
 
     bool ownsModule(Module* M) {
-      return (AddedModules.count(M) != 0) || (LoadedModules.count(M) != 0) ||
-             (FinalizedModules.count(M) != 0);
+      return AddedModules.contains(M) || LoadedModules.contains(M) ||
+             FinalizedModules.contains(M);
     }
 
     void markModuleAsLoaded(Module *M) {
diff --git a/llvm/lib/ExecutionEngine/Orc/CompileOnDemandLayer.cpp b/llvm/lib/ExecutionEngine/Orc/CompileOnDemandLayer.cpp
index 9e38dc36faae..68878f6729e9 100644
--- a/llvm/lib/ExecutionEngine/Orc/CompileOnDemandLayer.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/CompileOnDemandLayer.cpp
@@ -73,22 +73,21 @@ class PartitioningIRMaterializationUnit : public IRMaterializationUnit {
 public:
   PartitioningIRMaterializationUnit(ExecutionSession &ES,
                                     const IRSymbolMapper::ManglingOptions &MO,
-                                    ThreadSafeModule TSM, VModuleKey K,
+                                    ThreadSafeModule TSM,
                                     CompileOnDemandLayer &Parent)
-      : IRMaterializationUnit(ES, MO, std::move(TSM), std::move(K)),
-        Parent(Parent) {}
+      : IRMaterializationUnit(ES, MO, std::move(TSM)), Parent(Parent) {}
 
   PartitioningIRMaterializationUnit(
-      ThreadSafeModule TSM, VModuleKey K, SymbolFlagsMap SymbolFlags,
+      ThreadSafeModule TSM, SymbolFlagsMap SymbolFlags,
       SymbolStringPtr InitSymbol, SymbolNameToDefinitionMap SymbolToDefinition,
       CompileOnDemandLayer &Parent)
-      : IRMaterializationUnit(std::move(TSM), std::move(K),
-                              std::move(SymbolFlags), std::move(InitSymbol),
+      : IRMaterializationUnit(std::move(TSM), std::move(SymbolFlags),
+                              std::move(InitSymbol),
                               std::move(SymbolToDefinition)),
         Parent(Parent) {}
 
 private:
-  void materialize(MaterializationResponsibility R) override {
+  void materialize(std::unique_ptr<MaterializationResponsibility> R) override {
     Parent.emitPartition(std::move(R), std::move(TSM),
                          std::move(SymbolToDefinition));
   }
@@ -128,15 +127,15 @@ void CompileOnDemandLayer::setPartitionFunction(PartitionFunction Partition) {
 void CompileOnDemandLayer::setImplMap(ImplSymbolMap *Imp) {
   this->AliaseeImpls = Imp;
 }
-void CompileOnDemandLayer::emit(MaterializationResponsibility R,
-                                ThreadSafeModule TSM) {
+void CompileOnDemandLayer::emit(
+    std::unique_ptr<MaterializationResponsibility> R, ThreadSafeModule TSM) {
   assert(TSM && "Null module");
 
   auto &ES = getExecutionSession();
 
   // Sort the callables and non-callables, build re-exports and lodge the
   // actual module with the implementation dylib.
-  auto &PDR = getPerDylibResources(R.getTargetJITDylib());
+  auto &PDR = getPerDylibResources(R->getTargetJITDylib());
 
   SymbolAliasMap NonCallables;
   SymbolAliasMap Callables;
@@ -145,7 +144,7 @@ void CompileOnDemandLayer::emit(MaterializationResponsibility R,
     cleanUpModule(M);
   });
 
-  for (auto &KV : R.getSymbols()) {
+  for (auto &KV : R->getSymbols()) {
     auto &Name = KV.first;
     auto &Flags = KV.second;
     if (Flags.isCallable())
@@ -158,19 +157,29 @@ void CompileOnDemandLayer::emit(MaterializationResponsibility R,
   // implementation dylib.
   if (auto Err = PDR.getImplDylib().define(
           std::make_unique<PartitioningIRMaterializationUnit>(
-              ES, *getManglingOptions(), std::move(TSM), R.getVModuleKey(),
-              *this))) {
+              ES, *getManglingOptions(), std::move(TSM), *this))) {
     ES.reportError(std::move(Err));
-    R.failMaterialization();
+    R->failMaterialization();
     return;
   }
 
   if (!NonCallables.empty())
-    R.replace(reexports(PDR.getImplDylib(), std::move(NonCallables),
-                        JITDylibLookupFlags::MatchAllSymbols));
-  if (!Callables.empty())
-    R.replace(lazyReexports(LCTMgr, PDR.getISManager(), PDR.getImplDylib(),
-                            std::move(Callables), AliaseeImpls));
+    if (auto Err =
+            R->replace(reexports(PDR.getImplDylib(), std::move(NonCallables),
+                                 JITDylibLookupFlags::MatchAllSymbols))) {
+      getExecutionSession().reportError(std::move(Err));
+      R->failMaterialization();
+      return;
+    }
+  if (!Callables.empty()) {
+    if (auto Err = R->replace(
+            lazyReexports(LCTMgr, PDR.getISManager(), PDR.getImplDylib(),
+                          std::move(Callables), AliaseeImpls))) {
+      getExecutionSession().reportError(std::move(Err));
+      R->failMaterialization();
+      return;
+    }
+  }
 }
 
 CompileOnDemandLayer::PerDylibResources &
@@ -247,7 +256,7 @@ void CompileOnDemandLayer::expandPartition(GlobalValueSet &Partition) {
 }
 
 void CompileOnDemandLayer::emitPartition(
-    MaterializationResponsibility R, ThreadSafeModule TSM,
+    std::unique_ptr<MaterializationResponsibility> R, ThreadSafeModule TSM,
     IRMaterializationUnit::SymbolNameToDefinitionMap Defs) {
 
   // FIXME: Need a 'notify lazy-extracting/emitting' callback to tie the
@@ -257,8 +266,8 @@ void CompileOnDemandLayer::emitPartition(
 
   auto &ES = getExecutionSession();
   GlobalValueSet RequestedGVs;
-  for (auto &Name : R.getRequestedSymbols()) {
-    if (Name == R.getInitializerSymbol())
+  for (auto &Name : R->getRequestedSymbols()) {
+    if (Name == R->getInitializerSymbol())
       TSM.withModuleDo([&](Module &M) {
         for (auto &GV : getStaticInitGVs(M))
           RequestedGVs.insert(&GV);
@@ -285,9 +294,14 @@ void CompileOnDemandLayer::emitPartition(
 
   // If the partition is empty, return the whole module to the symbol table.
   if (GVsToExtract->empty()) {
-    R.replace(std::make_unique<PartitioningIRMaterializationUnit>(
-        std::move(TSM), R.getVModuleKey(), R.getSymbols(),
-        R.getInitializerSymbol(), std::move(Defs), *this));
+    if (auto Err =
+            R->replace(std::make_unique<PartitioningIRMaterializationUnit>(
+                std::move(TSM), R->getSymbols(), R->getInitializerSymbol(),
+                std::move(Defs), *this))) {
+      getExecutionSession().reportError(std::move(Err));
+      R->failMaterialization();
+      return;
+    }
     return;
   }
 
@@ -308,7 +322,7 @@ void CompileOnDemandLayer::emitPartition(
           IRSymbolMapper::add(ES, *getManglingOptions(),
                               PromotedGlobals, SymbolFlags);
 
-          if (auto Err = R.defineMaterializing(SymbolFlags))
+          if (auto Err = R->defineMaterializing(SymbolFlags))
             return std::move(Err);
         }
 
@@ -348,12 +362,16 @@ void CompileOnDemandLayer::emitPartition(
 
   if (!ExtractedTSM) {
     ES.reportError(ExtractedTSM.takeError());
-    R.failMaterialization();
+    R->failMaterialization();
     return;
   }
 
-  R.replace(std::make_unique<PartitioningIRMaterializationUnit>(
-      ES, *getManglingOptions(), std::move(TSM), R.getVModuleKey(), *this));
+  if (auto Err = R->replace(std::make_unique<PartitioningIRMaterializationUnit>(
+          ES, *getManglingOptions(), std::move(TSM), *this))) {
+    ES.reportError(std::move(Err));
+    R->failMaterialization();
+    return;
+  }
   BaseLayer.emit(std::move(R), std::move(*ExtractedTSM));
 }
 
diff --git a/llvm/lib/ExecutionEngine/Orc/Core.cpp b/llvm/lib/ExecutionEngine/Orc/Core.cpp
index bad13cfebbc6..dfb558808c32 100644
--- a/llvm/lib/ExecutionEngine/Orc/Core.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/Core.cpp
@@ -11,18 +11,19 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Config/llvm-config.h"
 #include "llvm/ExecutionEngine/Orc/DebugUtils.h"
-#include "llvm/ExecutionEngine/Orc/OrcError.h"
+#include "llvm/ExecutionEngine/Orc/Shared/OrcError.h"
+#include "llvm/Support/FormatVariadic.h"
+#include "llvm/Support/MSVCErrorWorkarounds.h"
 
 #include <condition_variable>
-#if LLVM_ENABLE_THREADS
 #include <future>
-#endif
 
 #define DEBUG_TYPE "orc"
 
 namespace llvm {
 namespace orc {
 
+char ResourceTrackerDefunct::ID = 0;
 char FailedToMaterialize::ID = 0;
 char SymbolsNotFound::ID = 0;
 char SymbolsCouldNotBeRemoved::ID = 0;
@@ -34,6 +35,45 @@ RegisterDependenciesFunction NoDependenciesToRegister =
 
 void MaterializationUnit::anchor() {}
 
+ResourceTracker::ResourceTracker(JITDylibSP JD) {
+  assert((reinterpret_cast<uintptr_t>(JD.get()) & 0x1) == 0 &&
+         "JITDylib must be two byte aligned");
+  JD->Retain();
+  JDAndFlag.store(reinterpret_cast<uintptr_t>(JD.get()));
+}
+
+ResourceTracker::~ResourceTracker() {
+  getJITDylib().getExecutionSession().destroyResourceTracker(*this);
+  getJITDylib().Release();
+}
+
+Error ResourceTracker::remove() {
+  return getJITDylib().getExecutionSession().removeResourceTracker(*this);
+}
+
+void ResourceTracker::transferTo(ResourceTracker &DstRT) {
+  getJITDylib().getExecutionSession().transferResourceTracker(DstRT, *this);
+}
+
+void ResourceTracker::makeDefunct() {
+  uintptr_t Val = JDAndFlag.load();
+  Val |= 0x1U;
+  JDAndFlag.store(Val);
+}
+
+ResourceManager::~ResourceManager() {}
+
+ResourceTrackerDefunct::ResourceTrackerDefunct(ResourceTrackerSP RT)
+    : RT(std::move(RT)) {}
+
+std::error_code ResourceTrackerDefunct::convertToErrorCode() const {
+  return orcError(OrcErrorCode::UnknownORCError);
+}
+
+void ResourceTrackerDefunct::log(raw_ostream &OS) const {
+  OS << "Resource tracker " << (void *)RT.get() << " became defunct";
+}
+
 FailedToMaterialize::FailedToMaterialize(
     std::shared_ptr<SymbolDependenceMap> Symbols)
     : Symbols(std::move(Symbols)) {
@@ -137,8 +177,6 @@ void AsynchronousSymbolQuery::handleComplete() {
   TmpNotifyComplete(std::move(ResolvedSymbols));
 }
 
-bool AsynchronousSymbolQuery::canStillFail() { return !!NotifyComplete; }
-
 void AsynchronousSymbolQuery::handleFailed(Error Err) {
   assert(QueryRegistrations.empty() && ResolvedSymbols.empty() &&
          OutstandingSymbolsCount == 0 &&
@@ -181,156 +219,9 @@ void AsynchronousSymbolQuery::detach() {
   QueryRegistrations.clear();
 }
 
-MaterializationResponsibility::~MaterializationResponsibility() {
-  assert(SymbolFlags.empty() &&
-         "All symbols should have been explicitly materialized or failed");
-}
-
-SymbolNameSet MaterializationResponsibility::getRequestedSymbols() const {
-  return JD->getRequestedSymbols(SymbolFlags);
-}
-
-Error MaterializationResponsibility::notifyResolved(const SymbolMap &Symbols) {
-  LLVM_DEBUG({
-    dbgs() << "In " << JD->getName() << " resolving " << Symbols << "\n";
-  });
-#ifndef NDEBUG
-  for (auto &KV : Symbols) {
-    auto WeakFlags = JITSymbolFlags::Weak | JITSymbolFlags::Common;
-    auto I = SymbolFlags.find(KV.first);
-    assert(I != SymbolFlags.end() &&
-           "Resolving symbol outside this responsibility set");
-    assert(!I->second.hasMaterializationSideEffectsOnly() &&
-           "Can't resolve materialization-side-effects-only symbol");
-    assert((KV.second.getFlags() & ~WeakFlags) == (I->second & ~WeakFlags) &&
-           "Resolving symbol with incorrect flags");
-  }
-#endif
-
-  return JD->resolve(Symbols);
-}
-
-Error MaterializationResponsibility::notifyEmitted() {
-
-  LLVM_DEBUG({
-    dbgs() << "In " << JD->getName() << " emitting " << SymbolFlags << "\n";
-  });
-
-  if (auto Err = JD->emit(SymbolFlags))
-    return Err;
-
-  SymbolFlags.clear();
-  return Error::success();
-}
-
-Error MaterializationResponsibility::defineMaterializing(
-    SymbolFlagsMap NewSymbolFlags) {
-
-  LLVM_DEBUG({
-    dbgs() << "In " << JD->getName() << " defining materializing symbols "
-           << NewSymbolFlags << "\n";
-  });
-  if (auto AcceptedDefs = JD->defineMaterializing(std::move(NewSymbolFlags))) {
-    // Add all newly accepted symbols to this responsibility object.
-    for (auto &KV : *AcceptedDefs)
-      SymbolFlags.insert(KV);
-    return Error::success();
-  } else
-    return AcceptedDefs.takeError();
-}
-
-void MaterializationResponsibility::failMaterialization() {
-
-  LLVM_DEBUG({
-    dbgs() << "In " << JD->getName() << " failing materialization for "
-           << SymbolFlags << "\n";
-  });
-
-  JITDylib::FailedSymbolsWorklist Worklist;
-
-  for (auto &KV : SymbolFlags)
-    Worklist.push_back(std::make_pair(JD.get(), KV.first));
-  SymbolFlags.clear();
-
-  JD->notifyFailed(std::move(Worklist));
-}
-
-void MaterializationResponsibility::replace(
-    std::unique_ptr<MaterializationUnit> MU) {
-
-  // If the replacement MU is empty then return.
-  if (MU->getSymbols().empty())
-    return;
-
-  for (auto &KV : MU->getSymbols()) {
-    assert(SymbolFlags.count(KV.first) &&
-           "Replacing definition outside this responsibility set");
-    SymbolFlags.erase(KV.first);
-  }
-
-  if (MU->getInitializerSymbol() == InitSymbol)
-    InitSymbol = nullptr;
-
-  LLVM_DEBUG(JD->getExecutionSession().runSessionLocked([&]() {
-    dbgs() << "In " << JD->getName() << " replacing symbols with " << *MU
-           << "\n";
-  }););
-
-  JD->replace(std::move(MU));
-}
-
-MaterializationResponsibility
-MaterializationResponsibility::delegate(const SymbolNameSet &Symbols,
-                                        VModuleKey NewKey) {
-
-  if (NewKey == VModuleKey())
-    NewKey = K;
-
-  SymbolStringPtr DelegatedInitSymbol;
-  SymbolFlagsMap DelegatedFlags;
-
-  for (auto &Name : Symbols) {
-    auto I = SymbolFlags.find(Name);
-    assert(I != SymbolFlags.end() &&
-           "Symbol is not tracked by this MaterializationResponsibility "
-           "instance");
-
-    DelegatedFlags[Name] = std::move(I->second);
-    if (Name == InitSymbol)
-      std::swap(InitSymbol, DelegatedInitSymbol);
-
-    SymbolFlags.erase(I);
-  }
-
-  return MaterializationResponsibility(JD, std::move(DelegatedFlags),
-                                       std::move(DelegatedInitSymbol),
-                                       std::move(NewKey));
-}
-
-void MaterializationResponsibility::addDependencies(
-    const SymbolStringPtr &Name, const SymbolDependenceMap &Dependencies) {
-  LLVM_DEBUG({
-    dbgs() << "Adding dependencies for " << Name << ": " << Dependencies
-           << "\n";
-  });
-  assert(SymbolFlags.count(Name) &&
-         "Symbol not covered by this MaterializationResponsibility instance");
-  JD->addDependencies(Name, Dependencies);
-}
-
-void MaterializationResponsibility::addDependenciesForAll(
-    const SymbolDependenceMap &Dependencies) {
-  LLVM_DEBUG({
-    dbgs() << "Adding dependencies for all symbols in " << SymbolFlags << ": "
-           << Dependencies << "\n";
-  });
-  for (auto &KV : SymbolFlags)
-    JD->addDependencies(KV.first, Dependencies);
-}
-
 AbsoluteSymbolsMaterializationUnit::AbsoluteSymbolsMaterializationUnit(
-    SymbolMap Symbols, VModuleKey K)
-    : MaterializationUnit(extractFlags(Symbols), nullptr, std::move(K)),
+    SymbolMap Symbols)
+    : MaterializationUnit(extractFlags(Symbols), nullptr),
       Symbols(std::move(Symbols)) {}
 
 StringRef AbsoluteSymbolsMaterializationUnit::getName() const {
@@ -338,10 +229,10 @@ StringRef AbsoluteSymbolsMaterializationUnit::getName() const {
 }
 
 void AbsoluteSymbolsMaterializationUnit::materialize(
-    MaterializationResponsibility R) {
+    std::unique_ptr<MaterializationResponsibility> R) {
   // No dependencies, so these calls can't fail.
-  cantFail(R.notifyResolved(Symbols));
-  cantFail(R.notifyEmitted());
+  cantFail(R->notifyResolved(Symbols));
+  cantFail(R->notifyEmitted());
 }
 
 void AbsoluteSymbolsMaterializationUnit::discard(const JITDylib &JD,
@@ -360,26 +251,25 @@ AbsoluteSymbolsMaterializationUnit::extractFlags(const SymbolMap &Symbols) {
 
 ReExportsMaterializationUnit::ReExportsMaterializationUnit(
     JITDylib *SourceJD, JITDylibLookupFlags SourceJDLookupFlags,
-    SymbolAliasMap Aliases, VModuleKey K)
-    : MaterializationUnit(extractFlags(Aliases), nullptr, std::move(K)),
-      SourceJD(SourceJD), SourceJDLookupFlags(SourceJDLookupFlags),
-      Aliases(std::move(Aliases)) {}
+    SymbolAliasMap Aliases)
+    : MaterializationUnit(extractFlags(Aliases), nullptr), SourceJD(SourceJD),
+      SourceJDLookupFlags(SourceJDLookupFlags), Aliases(std::move(Aliases)) {}
 
 StringRef ReExportsMaterializationUnit::getName() const {
   return "<Reexports>";
 }
 
 void ReExportsMaterializationUnit::materialize(
-    MaterializationResponsibility R) {
+    std::unique_ptr<MaterializationResponsibility> R) {
 
-  auto &ES = R.getTargetJITDylib().getExecutionSession();
-  JITDylib &TgtJD = R.getTargetJITDylib();
+  auto &ES = R->getTargetJITDylib().getExecutionSession();
+  JITDylib &TgtJD = R->getTargetJITDylib();
   JITDylib &SrcJD = SourceJD ? *SourceJD : TgtJD;
 
   // Find the set of requested aliases and aliasees. Return any unrequested
   // aliases back to the JITDylib so as to not prematurely materialize any
   // aliasees.
-  auto RequestedSymbols = R.getRequestedSymbols();
+  auto RequestedSymbols = R->getRequestedSymbols();
   SymbolAliasMap RequestedAliases;
 
   for (auto &Name : RequestedSymbols) {
@@ -398,19 +288,27 @@ void ReExportsMaterializationUnit::materialize(
   });
 
   if (!Aliases.empty()) {
-    if (SourceJD)
-      R.replace(reexports(*SourceJD, std::move(Aliases), SourceJDLookupFlags));
-    else
-      R.replace(symbolAliases(std::move(Aliases)));
+    auto Err = SourceJD ? R->replace(reexports(*SourceJD, std::move(Aliases),
+                                               SourceJDLookupFlags))
+                        : R->replace(symbolAliases(std::move(Aliases)));
+
+    if (Err) {
+      // FIXME: Should this be reported / treated as failure to materialize?
+      // Or should this be treated as a sanctioned bailing-out?
+      ES.reportError(std::move(Err));
+      R->failMaterialization();
+      return;
+    }
   }
 
   // The OnResolveInfo struct will hold the aliases and responsibilty for each
   // query in the list.
   struct OnResolveInfo {
-    OnResolveInfo(MaterializationResponsibility R, SymbolAliasMap Aliases)
+    OnResolveInfo(std::unique_ptr<MaterializationResponsibility> R,
+                  SymbolAliasMap Aliases)
         : R(std::move(R)), Aliases(std::move(Aliases)) {}
 
-    MaterializationResponsibility R;
+    std::unique_ptr<MaterializationResponsibility> R;
     SymbolAliasMap Aliases;
   };
 
@@ -450,8 +348,15 @@ void ReExportsMaterializationUnit::materialize(
 
     assert(!QuerySymbols.empty() && "Alias cycle detected!");
 
-    auto QueryInfo = std::make_shared<OnResolveInfo>(
-        R.delegate(ResponsibilitySymbols), std::move(QueryAliases));
+    auto NewR = R->delegate(ResponsibilitySymbols);
+    if (!NewR) {
+      ES.reportError(NewR.takeError());
+      R->failMaterialization();
+      return;
+    }
+
+    auto QueryInfo = std::make_shared<OnResolveInfo>(std::move(*NewR),
+                                                     std::move(QueryAliases));
     QueryInfos.push_back(
         make_pair(std::move(QuerySymbols), std::move(QueryInfo)));
   }
@@ -480,12 +385,12 @@ void ReExportsMaterializationUnit::materialize(
       for (auto &KV : QueryInfo->Aliases)
         if (SrcJDDeps.count(KV.second.Aliasee)) {
           PerAliasDeps = {KV.second.Aliasee};
-          QueryInfo->R.addDependencies(KV.first, PerAliasDepsMap);
+          QueryInfo->R->addDependencies(KV.first, PerAliasDepsMap);
         }
     };
 
     auto OnComplete = [QueryInfo](Expected<SymbolMap> Result) {
-      auto &ES = QueryInfo->R.getTargetJITDylib().getExecutionSession();
+      auto &ES = QueryInfo->R->getTargetJITDylib().getExecutionSession();
       if (Result) {
         SymbolMap ResolutionMap;
         for (auto &KV : QueryInfo->Aliases) {
@@ -499,19 +404,19 @@ void ReExportsMaterializationUnit::materialize(
           ResolutionMap[KV.first] = JITEvaluatedSymbol(
               (*Result)[KV.second.Aliasee].getAddress(), KV.second.AliasFlags);
         }
-        if (auto Err = QueryInfo->R.notifyResolved(ResolutionMap)) {
+        if (auto Err = QueryInfo->R->notifyResolved(ResolutionMap)) {
           ES.reportError(std::move(Err));
-          QueryInfo->R.failMaterialization();
+          QueryInfo->R->failMaterialization();
           return;
         }
-        if (auto Err = QueryInfo->R.notifyEmitted()) {
+        if (auto Err = QueryInfo->R->notifyEmitted()) {
           ES.reportError(std::move(Err));
-          QueryInfo->R.failMaterialization();
+          QueryInfo->R->failMaterialization();
           return;
         }
       } else {
         ES.reportError(Result.takeError());
-        QueryInfo->R.failMaterialization();
+        QueryInfo->R->failMaterialization();
       }
     };
 
@@ -538,20 +443,16 @@ ReExportsMaterializationUnit::extractFlags(const SymbolAliasMap &Aliases) {
   return SymbolFlags;
 }
 
-Expected<SymbolAliasMap>
-buildSimpleReexportsAliasMap(JITDylib &SourceJD, const SymbolNameSet &Symbols) {
+Expected<SymbolAliasMap> buildSimpleReexportsAliasMap(JITDylib &SourceJD,
+                                                      SymbolNameSet Symbols) {
   SymbolLookupSet LookupSet(Symbols);
-  auto Flags = SourceJD.lookupFlags(
-      LookupKind::Static, JITDylibLookupFlags::MatchAllSymbols, LookupSet);
+  auto Flags = SourceJD.getExecutionSession().lookupFlags(
+      LookupKind::Static, {{&SourceJD, JITDylibLookupFlags::MatchAllSymbols}},
+      SymbolLookupSet(std::move(Symbols)));
 
   if (!Flags)
     return Flags.takeError();
 
-  if (!LookupSet.empty()) {
-    LookupSet.sortByName();
-    return make_error<SymbolsNotFound>(LookupSet.getSymbolNames());
-  }
-
   SymbolAliasMap Result;
   for (auto &Name : Symbols) {
     assert(Flags->count(Name) && "Missing entry in flags map");
@@ -561,19 +462,100 @@ buildSimpleReexportsAliasMap(JITDylib &SourceJD, const SymbolNameSet &Symbols) {
   return Result;
 }
 
+class InProgressLookupState {
+public:
+  InProgressLookupState(LookupKind K, JITDylibSearchOrder SearchOrder,
+                        SymbolLookupSet LookupSet, SymbolState RequiredState)
+      : K(K), SearchOrder(std::move(SearchOrder)),
+        LookupSet(std::move(LookupSet)), RequiredState(RequiredState) {
+    DefGeneratorCandidates = this->LookupSet;
+  }
+  virtual ~InProgressLookupState() {}
+  virtual void complete(std::unique_ptr<InProgressLookupState> IPLS) = 0;
+  virtual void fail(Error Err) = 0;
+
+  LookupKind K;
+  JITDylibSearchOrder SearchOrder;
+  SymbolLookupSet LookupSet;
+  SymbolState RequiredState;
+
+  std::unique_lock<std::mutex> GeneratorLock;
+  size_t CurSearchOrderIndex = 0;
+  bool NewJITDylib = true;
+  SymbolLookupSet DefGeneratorCandidates;
+  SymbolLookupSet DefGeneratorNonCandidates;
+  std::vector<std::weak_ptr<DefinitionGenerator>> CurDefGeneratorStack;
+};
+
+class InProgressLookupFlagsState : public InProgressLookupState {
+public:
+  InProgressLookupFlagsState(
+      LookupKind K, JITDylibSearchOrder SearchOrder, SymbolLookupSet LookupSet,
+      unique_function<void(Expected<SymbolFlagsMap>)> OnComplete)
+      : InProgressLookupState(K, std::move(SearchOrder), std::move(LookupSet),
+                              SymbolState::NeverSearched),
+        OnComplete(std::move(OnComplete)) {}
+
+  void complete(std::unique_ptr<InProgressLookupState> IPLS) override {
+    GeneratorLock = {}; // Unlock and release.
+    auto &ES = SearchOrder.front().first->getExecutionSession();
+    ES.OL_completeLookupFlags(std::move(IPLS), std::move(OnComplete));
+  }
+
+  void fail(Error Err) override {
+    GeneratorLock = {}; // Unlock and release.
+    OnComplete(std::move(Err));
+  }
+
+private:
+  unique_function<void(Expected<SymbolFlagsMap>)> OnComplete;
+};
+
+class InProgressFullLookupState : public InProgressLookupState {
+public:
+  InProgressFullLookupState(LookupKind K, JITDylibSearchOrder SearchOrder,
+                            SymbolLookupSet LookupSet,
+                            SymbolState RequiredState,
+                            std::shared_ptr<AsynchronousSymbolQuery> Q,
+                            RegisterDependenciesFunction RegisterDependencies)
+      : InProgressLookupState(K, std::move(SearchOrder), std::move(LookupSet),
+                              RequiredState),
+        Q(std::move(Q)), RegisterDependencies(std::move(RegisterDependencies)) {
+  }
+
+  void complete(std::unique_ptr<InProgressLookupState> IPLS) override {
+    GeneratorLock = {}; // Unlock and release.
+    auto &ES = SearchOrder.front().first->getExecutionSession();
+    ES.OL_completeLookup(std::move(IPLS), std::move(Q),
+                         std::move(RegisterDependencies));
+  }
+
+  void fail(Error Err) override {
+    GeneratorLock = {};
+    Q->detach();
+    Q->handleFailed(std::move(Err));
+  }
+
+private:
+  std::shared_ptr<AsynchronousSymbolQuery> Q;
+  RegisterDependenciesFunction RegisterDependencies;
+};
+
 ReexportsGenerator::ReexportsGenerator(JITDylib &SourceJD,
                                        JITDylibLookupFlags SourceJDLookupFlags,
                                        SymbolPredicate Allow)
     : SourceJD(SourceJD), SourceJDLookupFlags(SourceJDLookupFlags),
       Allow(std::move(Allow)) {}
 
-Error ReexportsGenerator::tryToGenerate(LookupKind K, JITDylib &JD,
+Error ReexportsGenerator::tryToGenerate(LookupState &LS, LookupKind K,
+                                        JITDylib &JD,
                                         JITDylibLookupFlags JDLookupFlags,
                                         const SymbolLookupSet &LookupSet) {
   assert(&JD != &SourceJD && "Cannot re-export from the same dylib");
 
   // Use lookupFlags to find the subset of symbols that match our lookup.
-  auto Flags = SourceJD.lookupFlags(K, JDLookupFlags, LookupSet);
+  auto Flags = JD.getExecutionSession().lookupFlags(
+      K, {{&SourceJD, JDLookupFlags}}, LookupSet);
   if (!Flags)
     return Flags.takeError();
 
@@ -590,19 +572,63 @@ Error ReexportsGenerator::tryToGenerate(LookupKind K, JITDylib &JD,
   return JD.define(reexports(SourceJD, AliasMap, SourceJDLookupFlags));
 }
 
-JITDylib::DefinitionGenerator::~DefinitionGenerator() {}
+LookupState::LookupState(std::unique_ptr<InProgressLookupState> IPLS)
+    : IPLS(std::move(IPLS)) {}
 
-void JITDylib::removeGenerator(DefinitionGenerator &G) {
+void LookupState::reset(InProgressLookupState *IPLS) { this->IPLS.reset(IPLS); }
+
+LookupState::LookupState() = default;
+LookupState::LookupState(LookupState &&) = default;
+LookupState &LookupState::operator=(LookupState &&) = default;
+LookupState::~LookupState() = default;
+
+void LookupState::continueLookup(Error Err) {
+  assert(IPLS && "Cannot call continueLookup on empty LookupState");
+  auto &ES = IPLS->SearchOrder.begin()->first->getExecutionSession();
+  ES.OL_applyQueryPhase1(std::move(IPLS), std::move(Err));
+}
+
+DefinitionGenerator::~DefinitionGenerator() {}
+
+Error JITDylib::clear() {
+  std::vector<ResourceTrackerSP> TrackersToRemove;
   ES.runSessionLocked([&]() {
-    auto I = std::find_if(DefGenerators.begin(), DefGenerators.end(),
-                          [&](const std::unique_ptr<DefinitionGenerator> &H) {
-                            return H.get() == &G;
-                          });
-    assert(I != DefGenerators.end() && "Generator not found");
-    DefGenerators.erase(I);
+    for (auto &KV : TrackerSymbols)
+      TrackersToRemove.push_back(KV.first);
+    TrackersToRemove.push_back(getDefaultResourceTracker());
+  });
+
+  Error Err = Error::success();
+  for (auto &RT : TrackersToRemove)
+    Err = joinErrors(std::move(Err), RT->remove());
+  return Err;
+}
+
+ResourceTrackerSP JITDylib::getDefaultResourceTracker() {
+  return ES.runSessionLocked([this] {
+    if (!DefaultTracker)
+      DefaultTracker = new ResourceTracker(this);
+    return DefaultTracker;
+  });
+}
+
+ResourceTrackerSP JITDylib::createResourceTracker() {
+  return ES.runSessionLocked([this] {
+    ResourceTrackerSP RT = new ResourceTracker(this);
+    return RT;
   });
 }
 
+void JITDylib::removeGenerator(DefinitionGenerator &G) {
+  std::lock_guard<std::mutex> Lock(GeneratorsMutex);
+  auto I = llvm::find_if(DefGenerators,
+                         [&](const std::shared_ptr<DefinitionGenerator> &H) {
+                           return H.get() == &G;
+                         });
+  assert(I != DefGenerators.end() && "Generator not found");
+  DefGenerators.erase(I);
+}
+
 Expected<SymbolFlagsMap>
 JITDylib::defineMaterializing(SymbolFlagsMap SymbolFlags) {
 
@@ -652,11 +678,18 @@ JITDylib::defineMaterializing(SymbolFlagsMap SymbolFlags) {
   });
 }
 
-void JITDylib::replace(std::unique_ptr<MaterializationUnit> MU) {
+Error JITDylib::replace(MaterializationResponsibility &FromMR,
+                        std::unique_ptr<MaterializationUnit> MU) {
   assert(MU != nullptr && "Can not replace with a null MaterializationUnit");
+  std::unique_ptr<MaterializationUnit> MustRunMU;
+  std::unique_ptr<MaterializationResponsibility> MustRunMR;
 
-  auto MustRunMU =
-      ES.runSessionLocked([&, this]() -> std::unique_ptr<MaterializationUnit> {
+  auto Err =
+      ES.runSessionLocked([&, this]() -> Error {
+        auto RT = getTracker(FromMR);
+
+        if (RT->isDefunct())
+          return make_error<ResourceTrackerDefunct>(std::move(RT));
 
 #ifndef NDEBUG
         for (auto &KV : MU->getSymbols()) {
@@ -671,18 +704,27 @@ void JITDylib::replace(std::unique_ptr<MaterializationUnit> MU) {
         }
 #endif // NDEBUG
 
+        // If the tracker is defunct we need to bail out immediately.
+
         // If any symbol has pending queries against it then we need to
         // materialize MU immediately.
         for (auto &KV : MU->getSymbols()) {
           auto MII = MaterializingInfos.find(KV.first);
           if (MII != MaterializingInfos.end()) {
-            if (MII->second.hasQueriesPending())
-              return std::move(MU);
+            if (MII->second.hasQueriesPending()) {
+              MustRunMR = ES.createMaterializationResponsibility(
+                  *RT, std::move(MU->SymbolFlags), std::move(MU->InitSymbol));
+              MustRunMU = std::move(MU);
+              return Error::success();
+            }
           }
         }
 
         // Otherwise, make MU responsible for all the symbols.
-        auto UMI = std::make_shared<UnmaterializedInfo>(std::move(MU));
+        auto RTI = MRTrackers.find(&FromMR);
+        assert(RTI != MRTrackers.end() && "No tracker for FromMR");
+        auto UMI =
+            std::make_shared<UnmaterializedInfo>(std::move(MU), RTI->second);
         for (auto &KV : UMI->MU->getSymbols()) {
           auto SymI = Symbols.find(KV.first);
           assert(SymI->second.getState() == SymbolState::Materializing &&
@@ -700,14 +742,36 @@ void JITDylib::replace(std::unique_ptr<MaterializationUnit> MU) {
           UMIEntry = UMI;
         }
 
-        return nullptr;
+        return Error::success();
       });
 
+  if (Err)
+    return Err;
+
   if (MustRunMU) {
-    auto MR =
-        MustRunMU->createMaterializationResponsibility(shared_from_this());
-    ES.dispatchMaterialization(std::move(MustRunMU), std::move(MR));
+    assert(MustRunMR && "MustRunMU set implies MustRunMR set");
+    ES.dispatchMaterialization(std::move(MustRunMU), std::move(MustRunMR));
+  } else {
+    assert(!MustRunMR && "MustRunMU unset implies MustRunMR unset");
   }
+
+  return Error::success();
+}
+
+Expected<std::unique_ptr<MaterializationResponsibility>>
+JITDylib::delegate(MaterializationResponsibility &FromMR,
+                   SymbolFlagsMap SymbolFlags, SymbolStringPtr InitSymbol) {
+
+  return ES.runSessionLocked(
+      [&]() -> Expected<std::unique_ptr<MaterializationResponsibility>> {
+        auto RT = getTracker(FromMR);
+
+        if (RT->isDefunct())
+          return make_error<ResourceTrackerDefunct>(std::move(RT));
+
+        return ES.createMaterializationResponsibility(
+            *RT, std::move(SymbolFlags), std::move(InitSymbol));
+      });
 }
 
 SymbolNameSet
@@ -808,89 +872,93 @@ void JITDylib::addDependencies(const SymbolStringPtr &Name,
     Symbols[Name].setFlags(Symbols[Name].getFlags() | JITSymbolFlags::HasError);
 }
 
-Error JITDylib::resolve(const SymbolMap &Resolved) {
-  SymbolNameSet SymbolsInErrorState;
+Error JITDylib::resolve(MaterializationResponsibility &MR,
+                        const SymbolMap &Resolved) {
   AsynchronousSymbolQuerySet CompletedQueries;
 
-  ES.runSessionLocked([&, this]() {
-    struct WorklistEntry {
-      SymbolTable::iterator SymI;
-      JITEvaluatedSymbol ResolvedSym;
-    };
+  if (auto Err = ES.runSessionLocked([&, this]() -> Error {
+        auto RTI = MRTrackers.find(&MR);
+        assert(RTI != MRTrackers.end() && "No resource tracker for MR?");
+        if (RTI->second->isDefunct())
+          return make_error<ResourceTrackerDefunct>(RTI->second);
 
-    std::vector<WorklistEntry> Worklist;
-    Worklist.reserve(Resolved.size());
+        struct WorklistEntry {
+          SymbolTable::iterator SymI;
+          JITEvaluatedSymbol ResolvedSym;
+        };
 
-    // Build worklist and check for any symbols in the error state.
-    for (const auto &KV : Resolved) {
+        SymbolNameSet SymbolsInErrorState;
+        std::vector<WorklistEntry> Worklist;
+        Worklist.reserve(Resolved.size());
 
-      assert(!KV.second.getFlags().hasError() &&
-             "Resolution result can not have error flag set");
+        // Build worklist and check for any symbols in the error state.
+        for (const auto &KV : Resolved) {
 
-      auto SymI = Symbols.find(KV.first);
+          assert(!KV.second.getFlags().hasError() &&
+                 "Resolution result can not have error flag set");
 
-      assert(SymI != Symbols.end() && "Symbol not found");
-      assert(!SymI->second.hasMaterializerAttached() &&
-             "Resolving symbol with materializer attached?");
-      assert(SymI->second.getState() == SymbolState::Materializing &&
-             "Symbol should be materializing");
-      assert(SymI->second.getAddress() == 0 &&
-             "Symbol has already been resolved");
+          auto SymI = Symbols.find(KV.first);
 
-      if (SymI->second.getFlags().hasError())
-        SymbolsInErrorState.insert(KV.first);
-      else {
-        auto Flags = KV.second.getFlags();
-        Flags &= ~(JITSymbolFlags::Weak | JITSymbolFlags::Common);
-        assert(Flags == (SymI->second.getFlags() &
-                         ~(JITSymbolFlags::Weak | JITSymbolFlags::Common)) &&
-               "Resolved flags should match the declared flags");
+          assert(SymI != Symbols.end() && "Symbol not found");
+          assert(!SymI->second.hasMaterializerAttached() &&
+                 "Resolving symbol with materializer attached?");
+          assert(SymI->second.getState() == SymbolState::Materializing &&
+                 "Symbol should be materializing");
+          assert(SymI->second.getAddress() == 0 &&
+                 "Symbol has already been resolved");
 
-        Worklist.push_back(
-            {SymI, JITEvaluatedSymbol(KV.second.getAddress(), Flags)});
-      }
-    }
+          if (SymI->second.getFlags().hasError())
+            SymbolsInErrorState.insert(KV.first);
+          else {
+            auto Flags = KV.second.getFlags();
+            Flags &= ~(JITSymbolFlags::Weak | JITSymbolFlags::Common);
+            assert(Flags ==
+                       (SymI->second.getFlags() &
+                        ~(JITSymbolFlags::Weak | JITSymbolFlags::Common)) &&
+                   "Resolved flags should match the declared flags");
 
-    // If any symbols were in the error state then bail out.
-    if (!SymbolsInErrorState.empty())
-      return;
+            Worklist.push_back(
+                {SymI, JITEvaluatedSymbol(KV.second.getAddress(), Flags)});
+          }
+        }
 
-    while (!Worklist.empty()) {
-      auto SymI = Worklist.back().SymI;
-      auto ResolvedSym = Worklist.back().ResolvedSym;
-      Worklist.pop_back();
+        // If any symbols were in the error state then bail out.
+        if (!SymbolsInErrorState.empty()) {
+          auto FailedSymbolsDepMap = std::make_shared<SymbolDependenceMap>();
+          (*FailedSymbolsDepMap)[this] = std::move(SymbolsInErrorState);
+          return make_error<FailedToMaterialize>(
+              std::move(FailedSymbolsDepMap));
+        }
 
-      auto &Name = SymI->first;
+        while (!Worklist.empty()) {
+          auto SymI = Worklist.back().SymI;
+          auto ResolvedSym = Worklist.back().ResolvedSym;
+          Worklist.pop_back();
 
-      // Resolved symbols can not be weak: discard the weak flag.
-      JITSymbolFlags ResolvedFlags = ResolvedSym.getFlags();
-      SymI->second.setAddress(ResolvedSym.getAddress());
-      SymI->second.setFlags(ResolvedFlags);
-      SymI->second.setState(SymbolState::Resolved);
+          auto &Name = SymI->first;
 
-      auto MII = MaterializingInfos.find(Name);
-      if (MII == MaterializingInfos.end())
-        continue;
+          // Resolved symbols can not be weak: discard the weak flag.
+          JITSymbolFlags ResolvedFlags = ResolvedSym.getFlags();
+          SymI->second.setAddress(ResolvedSym.getAddress());
+          SymI->second.setFlags(ResolvedFlags);
+          SymI->second.setState(SymbolState::Resolved);
 
-      auto &MI = MII->second;
-      for (auto &Q : MI.takeQueriesMeeting(SymbolState::Resolved)) {
-        Q->notifySymbolMetRequiredState(Name, ResolvedSym);
-        Q->removeQueryDependence(*this, Name);
-        if (Q->isComplete())
-          CompletedQueries.insert(std::move(Q));
-      }
-    }
-  });
+          auto MII = MaterializingInfos.find(Name);
+          if (MII == MaterializingInfos.end())
+            continue;
 
-  assert((SymbolsInErrorState.empty() || CompletedQueries.empty()) &&
-         "Can't fail symbols and completed queries at the same time");
+          auto &MI = MII->second;
+          for (auto &Q : MI.takeQueriesMeeting(SymbolState::Resolved)) {
+            Q->notifySymbolMetRequiredState(Name, ResolvedSym);
+            Q->removeQueryDependence(*this, Name);
+            if (Q->isComplete())
+              CompletedQueries.insert(std::move(Q));
+          }
+        }
 
-  // If we failed any symbols then return an error.
-  if (!SymbolsInErrorState.empty()) {
-    auto FailedSymbolsDepMap = std::make_shared<SymbolDependenceMap>();
-    (*FailedSymbolsDepMap)[this] = std::move(SymbolsInErrorState);
-    return make_error<FailedToMaterialize>(std::move(FailedSymbolsDepMap));
-  }
+        return Error::success();
+      }))
+    return Err;
 
   // Otherwise notify all the completed queries.
   for (auto &Q : CompletedQueries) {
@@ -901,139 +969,145 @@ Error JITDylib::resolve(const SymbolMap &Resolved) {
   return Error::success();
 }
 
-Error JITDylib::emit(const SymbolFlagsMap &Emitted) {
+Error JITDylib::emit(MaterializationResponsibility &MR,
+                     const SymbolFlagsMap &Emitted) {
   AsynchronousSymbolQuerySet CompletedQueries;
-  SymbolNameSet SymbolsInErrorState;
   DenseMap<JITDylib *, SymbolNameVector> ReadySymbols;
 
-  ES.runSessionLocked([&, this]() {
-    std::vector<SymbolTable::iterator> Worklist;
+  if (auto Err = ES.runSessionLocked([&, this]() -> Error {
+        auto RTI = MRTrackers.find(&MR);
+        assert(RTI != MRTrackers.end() && "No resource tracker for MR?");
+        if (RTI->second->isDefunct())
+          return make_error<ResourceTrackerDefunct>(RTI->second);
 
-    // Scan to build worklist, record any symbols in the erorr state.
-    for (const auto &KV : Emitted) {
-      auto &Name = KV.first;
+        SymbolNameSet SymbolsInErrorState;
+        std::vector<SymbolTable::iterator> Worklist;
 
-      auto SymI = Symbols.find(Name);
-      assert(SymI != Symbols.end() && "No symbol table entry for Name");
+        // Scan to build worklist, record any symbols in the erorr state.
+        for (const auto &KV : Emitted) {
+          auto &Name = KV.first;
 
-      if (SymI->second.getFlags().hasError())
-        SymbolsInErrorState.insert(Name);
-      else
-        Worklist.push_back(SymI);
-    }
+          auto SymI = Symbols.find(Name);
+          assert(SymI != Symbols.end() && "No symbol table entry for Name");
 
-    // If any symbols were in the error state then bail out.
-    if (!SymbolsInErrorState.empty())
-      return;
+          if (SymI->second.getFlags().hasError())
+            SymbolsInErrorState.insert(Name);
+          else
+            Worklist.push_back(SymI);
+        }
 
-    // Otherwise update dependencies and move to the emitted state.
-    while (!Worklist.empty()) {
-      auto SymI = Worklist.back();
-      Worklist.pop_back();
+        // If any symbols were in the error state then bail out.
+        if (!SymbolsInErrorState.empty()) {
+          auto FailedSymbolsDepMap = std::make_shared<SymbolDependenceMap>();
+          (*FailedSymbolsDepMap)[this] = std::move(SymbolsInErrorState);
+          return make_error<FailedToMaterialize>(
+              std::move(FailedSymbolsDepMap));
+        }
 
-      auto &Name = SymI->first;
-      auto &SymEntry = SymI->second;
+        // Otherwise update dependencies and move to the emitted state.
+        while (!Worklist.empty()) {
+          auto SymI = Worklist.back();
+          Worklist.pop_back();
 
-      // Move symbol to the emitted state.
-      assert(((SymEntry.getFlags().hasMaterializationSideEffectsOnly() &&
-               SymEntry.getState() == SymbolState::Materializing) ||
-              SymEntry.getState() == SymbolState::Resolved) &&
-             "Emitting from state other than Resolved");
-      SymEntry.setState(SymbolState::Emitted);
+          auto &Name = SymI->first;
+          auto &SymEntry = SymI->second;
 
-      auto MII = MaterializingInfos.find(Name);
+          // Move symbol to the emitted state.
+          assert(((SymEntry.getFlags().hasMaterializationSideEffectsOnly() &&
+                   SymEntry.getState() == SymbolState::Materializing) ||
+                  SymEntry.getState() == SymbolState::Resolved) &&
+                 "Emitting from state other than Resolved");
+          SymEntry.setState(SymbolState::Emitted);
 
-      // If this symbol has no MaterializingInfo then it's trivially ready.
-      // Update its state and continue.
-      if (MII == MaterializingInfos.end()) {
-        SymEntry.setState(SymbolState::Ready);
-        continue;
-      }
+          auto MII = MaterializingInfos.find(Name);
 
-      auto &MI = MII->second;
+          // If this symbol has no MaterializingInfo then it's trivially ready.
+          // Update its state and continue.
+          if (MII == MaterializingInfos.end()) {
+            SymEntry.setState(SymbolState::Ready);
+            continue;
+          }
 
-      // For each dependant, transfer this node's emitted dependencies to
-      // it. If the dependant node is ready (i.e. has no unemitted
-      // dependencies) then notify any pending queries.
-      for (auto &KV : MI.Dependants) {
-        auto &DependantJD = *KV.first;
-        auto &DependantJDReadySymbols = ReadySymbols[&DependantJD];
-        for (auto &DependantName : KV.second) {
-          auto DependantMII =
-              DependantJD.MaterializingInfos.find(DependantName);
-          assert(DependantMII != DependantJD.MaterializingInfos.end() &&
-                 "Dependant should have MaterializingInfo");
+          auto &MI = MII->second;
 
-          auto &DependantMI = DependantMII->second;
+          // For each dependant, transfer this node's emitted dependencies to
+          // it. If the dependant node is ready (i.e. has no unemitted
+          // dependencies) then notify any pending queries.
+          for (auto &KV : MI.Dependants) {
+            auto &DependantJD = *KV.first;
+            auto &DependantJDReadySymbols = ReadySymbols[&DependantJD];
+            for (auto &DependantName : KV.second) {
+              auto DependantMII =
+                  DependantJD.MaterializingInfos.find(DependantName);
+              assert(DependantMII != DependantJD.MaterializingInfos.end() &&
+                     "Dependant should have MaterializingInfo");
 
-          // Remove the dependant's dependency on this node.
-          assert(DependantMI.UnemittedDependencies.count(this) &&
-                 "Dependant does not have an unemitted dependencies record for "
-                 "this JITDylib");
-          assert(DependantMI.UnemittedDependencies[this].count(Name) &&
-                 "Dependant does not count this symbol as a dependency?");
+              auto &DependantMI = DependantMII->second;
 
-          DependantMI.UnemittedDependencies[this].erase(Name);
-          if (DependantMI.UnemittedDependencies[this].empty())
-            DependantMI.UnemittedDependencies.erase(this);
+              // Remove the dependant's dependency on this node.
+              assert(DependantMI.UnemittedDependencies.count(this) &&
+                     "Dependant does not have an unemitted dependencies record "
+                     "for "
+                     "this JITDylib");
+              assert(DependantMI.UnemittedDependencies[this].count(Name) &&
+                     "Dependant does not count this symbol as a dependency?");
 
-          // Transfer unemitted dependencies from this node to the dependant.
-          DependantJD.transferEmittedNodeDependencies(DependantMI,
-                                                      DependantName, MI);
+              DependantMI.UnemittedDependencies[this].erase(Name);
+              if (DependantMI.UnemittedDependencies[this].empty())
+                DependantMI.UnemittedDependencies.erase(this);
 
-          auto DependantSymI = DependantJD.Symbols.find(DependantName);
-          assert(DependantSymI != DependantJD.Symbols.end() &&
-                 "Dependant has no entry in the Symbols table");
-          auto &DependantSymEntry = DependantSymI->second;
+              // Transfer unemitted dependencies from this node to the
+              // dependant.
+              DependantJD.transferEmittedNodeDependencies(DependantMI,
+                                                          DependantName, MI);
 
-          // If the dependant is emitted and this node was the last of its
-          // unemitted dependencies then the dependant node is now ready, so
-          // notify any pending queries on the dependant node.
-          if (DependantSymEntry.getState() == SymbolState::Emitted &&
-              DependantMI.UnemittedDependencies.empty()) {
-            assert(DependantMI.Dependants.empty() &&
-                   "Dependants should be empty by now");
+              auto DependantSymI = DependantJD.Symbols.find(DependantName);
+              assert(DependantSymI != DependantJD.Symbols.end() &&
+                     "Dependant has no entry in the Symbols table");
+              auto &DependantSymEntry = DependantSymI->second;
 
-            // Since this dependant is now ready, we erase its MaterializingInfo
-            // and update its materializing state.
-            DependantSymEntry.setState(SymbolState::Ready);
-            DependantJDReadySymbols.push_back(DependantName);
+              // If the dependant is emitted and this node was the last of its
+              // unemitted dependencies then the dependant node is now ready, so
+              // notify any pending queries on the dependant node.
+              if (DependantSymEntry.getState() == SymbolState::Emitted &&
+                  DependantMI.UnemittedDependencies.empty()) {
+                assert(DependantMI.Dependants.empty() &&
+                       "Dependants should be empty by now");
 
-            for (auto &Q : DependantMI.takeQueriesMeeting(SymbolState::Ready)) {
-              Q->notifySymbolMetRequiredState(
-                  DependantName, DependantSymI->second.getSymbol());
+                // Since this dependant is now ready, we erase its
+                // MaterializingInfo and update its materializing state.
+                DependantSymEntry.setState(SymbolState::Ready);
+                DependantJDReadySymbols.push_back(DependantName);
+
+                for (auto &Q :
+                     DependantMI.takeQueriesMeeting(SymbolState::Ready)) {
+                  Q->notifySymbolMetRequiredState(
+                      DependantName, DependantSymI->second.getSymbol());
+                  if (Q->isComplete())
+                    CompletedQueries.insert(Q);
+                  Q->removeQueryDependence(DependantJD, DependantName);
+                }
+              }
+            }
+          }
+
+          auto &ThisJDReadySymbols = ReadySymbols[this];
+          MI.Dependants.clear();
+          if (MI.UnemittedDependencies.empty()) {
+            SymI->second.setState(SymbolState::Ready);
+            ThisJDReadySymbols.push_back(Name);
+            for (auto &Q : MI.takeQueriesMeeting(SymbolState::Ready)) {
+              Q->notifySymbolMetRequiredState(Name, SymI->second.getSymbol());
               if (Q->isComplete())
                 CompletedQueries.insert(Q);
-              Q->removeQueryDependence(DependantJD, DependantName);
+              Q->removeQueryDependence(*this, Name);
             }
           }
         }
-      }
 
-      auto &ThisJDReadySymbols = ReadySymbols[this];
-      MI.Dependants.clear();
-      if (MI.UnemittedDependencies.empty()) {
-        SymI->second.setState(SymbolState::Ready);
-        ThisJDReadySymbols.push_back(Name);
-        for (auto &Q : MI.takeQueriesMeeting(SymbolState::Ready)) {
-          Q->notifySymbolMetRequiredState(Name, SymI->second.getSymbol());
-          if (Q->isComplete())
-            CompletedQueries.insert(Q);
-          Q->removeQueryDependence(*this, Name);
-        }
-      }
-    }
-  });
-
-  assert((SymbolsInErrorState.empty() || CompletedQueries.empty()) &&
-         "Can't fail symbols and completed queries at the same time");
-
-  // If we failed any symbols then return an error.
-  if (!SymbolsInErrorState.empty()) {
-    auto FailedSymbolsDepMap = std::make_shared<SymbolDependenceMap>();
-    (*FailedSymbolsDepMap)[this] = std::move(SymbolsInErrorState);
-    return make_error<FailedToMaterialize>(std::move(FailedSymbolsDepMap));
-  }
+        return Error::success();
+      }))
+    return Err;
 
   // Otherwise notify all the completed queries.
   for (auto &Q : CompletedQueries) {
@@ -1044,120 +1118,122 @@ Error JITDylib::emit(const SymbolFlagsMap &Emitted) {
   return Error::success();
 }
 
-void JITDylib::notifyFailed(FailedSymbolsWorklist Worklist) {
+void JITDylib::unlinkMaterializationResponsibility(
+    MaterializationResponsibility &MR) {
+  ES.runSessionLocked([&]() {
+    auto I = MRTrackers.find(&MR);
+    assert(I != MRTrackers.end() && "MaterializationResponsibility not linked");
+    MRTrackers.erase(I);
+  });
+}
+
+std::pair<JITDylib::AsynchronousSymbolQuerySet,
+          std::shared_ptr<SymbolDependenceMap>>
+JITDylib::failSymbols(FailedSymbolsWorklist Worklist) {
   AsynchronousSymbolQuerySet FailedQueries;
   auto FailedSymbolsMap = std::make_shared<SymbolDependenceMap>();
 
-  // Failing no symbols is a no-op.
-  if (Worklist.empty())
-    return;
-
-  auto &ES = Worklist.front().first->getExecutionSession();
-
-  ES.runSessionLocked([&]() {
-    while (!Worklist.empty()) {
-      assert(Worklist.back().first && "Failed JITDylib can not be null");
-      auto &JD = *Worklist.back().first;
-      auto Name = std::move(Worklist.back().second);
-      Worklist.pop_back();
+  while (!Worklist.empty()) {
+    assert(Worklist.back().first && "Failed JITDylib can not be null");
+    auto &JD = *Worklist.back().first;
+    auto Name = std::move(Worklist.back().second);
+    Worklist.pop_back();
 
-      (*FailedSymbolsMap)[&JD].insert(Name);
+    (*FailedSymbolsMap)[&JD].insert(Name);
 
-      assert(JD.Symbols.count(Name) && "No symbol table entry for Name");
-      auto &Sym = JD.Symbols[Name];
+    assert(JD.Symbols.count(Name) && "No symbol table entry for Name");
+    auto &Sym = JD.Symbols[Name];
 
-      // Move the symbol into the error state.
-      // Note that this may be redundant: The symbol might already have been
-      // moved to this state in response to the failure of a dependence.
-      Sym.setFlags(Sym.getFlags() | JITSymbolFlags::HasError);
+    // Move the symbol into the error state.
+    // Note that this may be redundant: The symbol might already have been
+    // moved to this state in response to the failure of a dependence.
+    Sym.setFlags(Sym.getFlags() | JITSymbolFlags::HasError);
 
-      // FIXME: Come up with a sane mapping of state to
-      // presence-of-MaterializingInfo so that we can assert presence / absence
-      // here, rather than testing it.
-      auto MII = JD.MaterializingInfos.find(Name);
+    // FIXME: Come up with a sane mapping of state to
+    // presence-of-MaterializingInfo so that we can assert presence / absence
+    // here, rather than testing it.
+    auto MII = JD.MaterializingInfos.find(Name);
 
-      if (MII == JD.MaterializingInfos.end())
-        continue;
+    if (MII == JD.MaterializingInfos.end())
+      continue;
 
-      auto &MI = MII->second;
+    auto &MI = MII->second;
 
-      // Move all dependants to the error state and disconnect from them.
-      for (auto &KV : MI.Dependants) {
-        auto &DependantJD = *KV.first;
-        for (auto &DependantName : KV.second) {
-          assert(DependantJD.Symbols.count(DependantName) &&
-                 "No symbol table entry for DependantName");
-          auto &DependantSym = DependantJD.Symbols[DependantName];
-          DependantSym.setFlags(DependantSym.getFlags() |
-                                JITSymbolFlags::HasError);
+    // Move all dependants to the error state and disconnect from them.
+    for (auto &KV : MI.Dependants) {
+      auto &DependantJD = *KV.first;
+      for (auto &DependantName : KV.second) {
+        assert(DependantJD.Symbols.count(DependantName) &&
+               "No symbol table entry for DependantName");
+        auto &DependantSym = DependantJD.Symbols[DependantName];
+        DependantSym.setFlags(DependantSym.getFlags() |
+                              JITSymbolFlags::HasError);
 
-          assert(DependantJD.MaterializingInfos.count(DependantName) &&
-                 "No MaterializingInfo for dependant");
-          auto &DependantMI = DependantJD.MaterializingInfos[DependantName];
+        assert(DependantJD.MaterializingInfos.count(DependantName) &&
+               "No MaterializingInfo for dependant");
+        auto &DependantMI = DependantJD.MaterializingInfos[DependantName];
 
-          auto UnemittedDepI = DependantMI.UnemittedDependencies.find(&JD);
-          assert(UnemittedDepI != DependantMI.UnemittedDependencies.end() &&
-                 "No UnemittedDependencies entry for this JITDylib");
-          assert(UnemittedDepI->second.count(Name) &&
-                 "No UnemittedDependencies entry for this symbol");
-          UnemittedDepI->second.erase(Name);
-          if (UnemittedDepI->second.empty())
-            DependantMI.UnemittedDependencies.erase(UnemittedDepI);
+        auto UnemittedDepI = DependantMI.UnemittedDependencies.find(&JD);
+        assert(UnemittedDepI != DependantMI.UnemittedDependencies.end() &&
+               "No UnemittedDependencies entry for this JITDylib");
+        assert(UnemittedDepI->second.count(Name) &&
+               "No UnemittedDependencies entry for this symbol");
+        UnemittedDepI->second.erase(Name);
+        if (UnemittedDepI->second.empty())
+          DependantMI.UnemittedDependencies.erase(UnemittedDepI);
 
-          // If this symbol is already in the emitted state then we need to
-          // take responsibility for failing its queries, so add it to the
-          // worklist.
-          if (DependantSym.getState() == SymbolState::Emitted) {
-            assert(DependantMI.Dependants.empty() &&
-                   "Emitted symbol should not have dependants");
-            Worklist.push_back(std::make_pair(&DependantJD, DependantName));
-          }
+        // If this symbol is already in the emitted state then we need to
+        // take responsibility for failing its queries, so add it to the
+        // worklist.
+        if (DependantSym.getState() == SymbolState::Emitted) {
+          assert(DependantMI.Dependants.empty() &&
+                 "Emitted symbol should not have dependants");
+          Worklist.push_back(std::make_pair(&DependantJD, DependantName));
         }
       }
-      MI.Dependants.clear();
-
-      // Disconnect from all unemitted depenencies.
-      for (auto &KV : MI.UnemittedDependencies) {
-        auto &UnemittedDepJD = *KV.first;
-        for (auto &UnemittedDepName : KV.second) {
-          auto UnemittedDepMII =
-              UnemittedDepJD.MaterializingInfos.find(UnemittedDepName);
-          assert(UnemittedDepMII != UnemittedDepJD.MaterializingInfos.end() &&
-                 "Missing MII for unemitted dependency");
-          assert(UnemittedDepMII->second.Dependants.count(&JD) &&
-                 "JD not listed as a dependant of unemitted dependency");
-          assert(UnemittedDepMII->second.Dependants[&JD].count(Name) &&
-                 "Name is not listed as a dependant of unemitted dependency");
-          UnemittedDepMII->second.Dependants[&JD].erase(Name);
-          if (UnemittedDepMII->second.Dependants[&JD].empty())
-            UnemittedDepMII->second.Dependants.erase(&JD);
-        }
-      }
-      MI.UnemittedDependencies.clear();
+    }
+    MI.Dependants.clear();
 
-      // Collect queries to be failed for this MII.
-      AsynchronousSymbolQueryList ToDetach;
-      for (auto &Q : MII->second.pendingQueries()) {
-        // Add the query to the list to be failed and detach it.
-        FailedQueries.insert(Q);
-        ToDetach.push_back(Q);
+    // Disconnect from all unemitted depenencies.
+    for (auto &KV : MI.UnemittedDependencies) {
+      auto &UnemittedDepJD = *KV.first;
+      for (auto &UnemittedDepName : KV.second) {
+        auto UnemittedDepMII =
+            UnemittedDepJD.MaterializingInfos.find(UnemittedDepName);
+        assert(UnemittedDepMII != UnemittedDepJD.MaterializingInfos.end() &&
+               "Missing MII for unemitted dependency");
+        assert(UnemittedDepMII->second.Dependants.count(&JD) &&
+               "JD not listed as a dependant of unemitted dependency");
+        assert(UnemittedDepMII->second.Dependants[&JD].count(Name) &&
+               "Name is not listed as a dependant of unemitted dependency");
+        UnemittedDepMII->second.Dependants[&JD].erase(Name);
+        if (UnemittedDepMII->second.Dependants[&JD].empty())
+          UnemittedDepMII->second.Dependants.erase(&JD);
       }
-      for (auto &Q : ToDetach)
-        Q->detach();
+    }
+    MI.UnemittedDependencies.clear();
 
-      assert(MI.Dependants.empty() &&
-             "Can not delete MaterializingInfo with dependants still attached");
-      assert(MI.UnemittedDependencies.empty() &&
-             "Can not delete MaterializingInfo with unemitted dependencies "
-             "still attached");
-      assert(!MI.hasQueriesPending() &&
-             "Can not delete MaterializingInfo with queries pending");
-      JD.MaterializingInfos.erase(MII);
+    // Collect queries to be failed for this MII.
+    AsynchronousSymbolQueryList ToDetach;
+    for (auto &Q : MII->second.pendingQueries()) {
+      // Add the query to the list to be failed and detach it.
+      FailedQueries.insert(Q);
+      ToDetach.push_back(Q);
     }
-  });
+    for (auto &Q : ToDetach)
+      Q->detach();
 
-  for (auto &Q : FailedQueries)
-    Q->handleFailed(make_error<FailedToMaterialize>(FailedSymbolsMap));
+    assert(MI.Dependants.empty() &&
+           "Can not delete MaterializingInfo with dependants still attached");
+    assert(MI.UnemittedDependencies.empty() &&
+           "Can not delete MaterializingInfo with unemitted dependencies "
+           "still attached");
+    assert(!MI.hasQueriesPending() &&
+           "Can not delete MaterializingInfo with queries pending");
+    JD.MaterializingInfos.erase(MII);
+  }
+
+  return std::make_pair(std::move(FailedQueries), std::move(FailedSymbolsMap));
 }
 
 void JITDylib::setLinkOrder(JITDylibSearchOrder NewLinkOrder,
@@ -1168,8 +1244,7 @@ void JITDylib::setLinkOrder(JITDylibSearchOrder NewLinkOrder,
       if (NewLinkOrder.empty() || NewLinkOrder.front().first != this)
         LinkOrder.push_back(
             std::make_pair(this, JITDylibLookupFlags::MatchAllSymbols));
-      LinkOrder.insert(LinkOrder.end(), NewLinkOrder.begin(),
-                       NewLinkOrder.end());
+      llvm::append_range(LinkOrder, NewLinkOrder);
     } else
       LinkOrder = std::move(NewLinkOrder);
   });
@@ -1192,10 +1267,10 @@ void JITDylib::replaceInLinkOrder(JITDylib &OldJD, JITDylib &NewJD,
 
 void JITDylib::removeFromLinkOrder(JITDylib &JD) {
   ES.runSessionLocked([&]() {
-    auto I = std::find_if(LinkOrder.begin(), LinkOrder.end(),
-                          [&](const JITDylibSearchOrder::value_type &KV) {
-                            return KV.first == &JD;
-                          });
+    auto I = llvm::find_if(LinkOrder,
+                           [&](const JITDylibSearchOrder::value_type &KV) {
+                             return KV.first == &JD;
+                           });
     if (I != LinkOrder.end())
       LinkOrder.erase(I);
   });
@@ -1257,279 +1332,6 @@ Error JITDylib::remove(const SymbolNameSet &Names) {
   });
 }
 
-Expected<SymbolFlagsMap>
-JITDylib::lookupFlags(LookupKind K, JITDylibLookupFlags JDLookupFlags,
-                      SymbolLookupSet LookupSet) {
-  return ES.runSessionLocked([&, this]() -> Expected<SymbolFlagsMap> {
-    SymbolFlagsMap Result;
-    lookupFlagsImpl(Result, K, JDLookupFlags, LookupSet);
-
-    // Run any definition generators.
-    for (auto &DG : DefGenerators) {
-
-      // Bail out early if we found everything.
-      if (LookupSet.empty())
-        break;
-
-      // Run this generator.
-      if (auto Err = DG->tryToGenerate(K, *this, JDLookupFlags, LookupSet))
-        return std::move(Err);
-
-      // Re-try the search.
-      lookupFlagsImpl(Result, K, JDLookupFlags, LookupSet);
-    }
-
-    return Result;
-  });
-}
-
-void JITDylib::lookupFlagsImpl(SymbolFlagsMap &Result, LookupKind K,
-                               JITDylibLookupFlags JDLookupFlags,
-                               SymbolLookupSet &LookupSet) {
-
-  LookupSet.forEachWithRemoval(
-      [&](const SymbolStringPtr &Name, SymbolLookupFlags Flags) -> bool {
-        auto I = Symbols.find(Name);
-        if (I == Symbols.end())
-          return false;
-        assert(!Result.count(Name) && "Symbol already present in Flags map");
-        Result[Name] = I->second.getFlags();
-        return true;
-      });
-}
-
-Error JITDylib::lodgeQuery(MaterializationUnitList &MUs,
-                           std::shared_ptr<AsynchronousSymbolQuery> &Q,
-                           LookupKind K, JITDylibLookupFlags JDLookupFlags,
-                           SymbolLookupSet &Unresolved) {
-  assert(Q && "Query can not be null");
-
-  if (auto Err = lodgeQueryImpl(MUs, Q, K, JDLookupFlags, Unresolved))
-    return Err;
-
-  // Run any definition generators.
-  for (auto &DG : DefGenerators) {
-
-    // Bail out early if we have resolved everything.
-    if (Unresolved.empty())
-      break;
-
-    // Run the generator.
-    if (auto Err = DG->tryToGenerate(K, *this, JDLookupFlags, Unresolved))
-      return Err;
-
-    // Lodge query. This can not fail as any new definitions were added
-    // by the generator under the session locked. Since they can't have
-    // started materializing yet they can not have failed.
-    cantFail(lodgeQueryImpl(MUs, Q, K, JDLookupFlags, Unresolved));
-  }
-
-  return Error::success();
-}
-
-Error JITDylib::lodgeQueryImpl(MaterializationUnitList &MUs,
-                               std::shared_ptr<AsynchronousSymbolQuery> &Q,
-                               LookupKind K, JITDylibLookupFlags JDLookupFlags,
-                               SymbolLookupSet &Unresolved) {
-
-  return Unresolved.forEachWithRemoval(
-      [&](const SymbolStringPtr &Name,
-          SymbolLookupFlags SymLookupFlags) -> Expected<bool> {
-        // Search for name in symbols. If not found then continue without
-        // removal.
-        auto SymI = Symbols.find(Name);
-        if (SymI == Symbols.end())
-          return false;
-
-        // If we match against a materialization-side-effects only symbol then
-        // make sure it is weakly-referenced. Otherwise bail out with an error.
-        if (SymI->second.getFlags().hasMaterializationSideEffectsOnly() &&
-            SymLookupFlags != SymbolLookupFlags::WeaklyReferencedSymbol)
-          return make_error<SymbolsNotFound>(SymbolNameVector({Name}));
-
-        // If this is a non exported symbol and we're matching exported symbols
-        // only then skip this symbol without removal.
-        if (!SymI->second.getFlags().isExported() &&
-            JDLookupFlags == JITDylibLookupFlags::MatchExportedSymbolsOnly)
-          return false;
-
-        // If we matched against this symbol but it is in the error state then
-        // bail out and treat it as a failure to materialize.
-        if (SymI->second.getFlags().hasError()) {
-          auto FailedSymbolsMap = std::make_shared<SymbolDependenceMap>();
-          (*FailedSymbolsMap)[this] = {Name};
-          return make_error<FailedToMaterialize>(std::move(FailedSymbolsMap));
-        }
-
-        // If this symbol already meets the required state for then notify the
-        // query, then remove the symbol and continue.
-        if (SymI->second.getState() >= Q->getRequiredState()) {
-          Q->notifySymbolMetRequiredState(Name, SymI->second.getSymbol());
-          return true;
-        }
-
-        // Otherwise this symbol does not yet meet the required state. Check
-        // whether it has a materializer attached, and if so prepare to run it.
-        if (SymI->second.hasMaterializerAttached()) {
-          assert(SymI->second.getAddress() == 0 &&
-                 "Symbol not resolved but already has address?");
-          auto UMII = UnmaterializedInfos.find(Name);
-          assert(UMII != UnmaterializedInfos.end() &&
-                 "Lazy symbol should have UnmaterializedInfo");
-          auto MU = std::move(UMII->second->MU);
-          assert(MU != nullptr && "Materializer should not be null");
-
-          // Move all symbols associated with this MaterializationUnit into
-          // materializing state.
-          for (auto &KV : MU->getSymbols()) {
-            auto SymK = Symbols.find(KV.first);
-            SymK->second.setMaterializerAttached(false);
-            SymK->second.setState(SymbolState::Materializing);
-            UnmaterializedInfos.erase(KV.first);
-          }
-
-          // Add MU to the list of MaterializationUnits to be materialized.
-          MUs.push_back(std::move(MU));
-        }
-
-        // Add the query to the PendingQueries list and continue, deleting the
-        // element.
-        assert(SymI->second.getState() != SymbolState::NeverSearched &&
-               SymI->second.getState() != SymbolState::Ready &&
-               "By this line the symbol should be materializing");
-        auto &MI = MaterializingInfos[Name];
-        MI.addQuery(Q);
-        Q->addQueryDependence(*this, Name);
-        return true;
-      });
-}
-
-Expected<SymbolNameSet>
-JITDylib::legacyLookup(std::shared_ptr<AsynchronousSymbolQuery> Q,
-                       SymbolNameSet Names) {
-  assert(Q && "Query can not be null");
-
-  ES.runOutstandingMUs();
-
-  bool QueryComplete = false;
-  std::vector<std::unique_ptr<MaterializationUnit>> MUs;
-
-  SymbolLookupSet Unresolved(Names);
-  auto Err = ES.runSessionLocked([&, this]() -> Error {
-    QueryComplete = lookupImpl(Q, MUs, Unresolved);
-
-    // Run any definition generators.
-    for (auto &DG : DefGenerators) {
-
-      // Bail out early if we have resolved everything.
-      if (Unresolved.empty())
-        break;
-
-      assert(!QueryComplete && "query complete but unresolved symbols remain?");
-      if (auto Err = DG->tryToGenerate(LookupKind::Static, *this,
-                                       JITDylibLookupFlags::MatchAllSymbols,
-                                       Unresolved))
-        return Err;
-
-      if (!Unresolved.empty())
-        QueryComplete = lookupImpl(Q, MUs, Unresolved);
-    }
-    return Error::success();
-  });
-
-  if (Err)
-    return std::move(Err);
-
-  assert((MUs.empty() || !QueryComplete) &&
-         "If action flags are set, there should be no work to do (so no MUs)");
-
-  if (QueryComplete)
-    Q->handleComplete();
-
-  // FIXME: Swap back to the old code below once RuntimeDyld works with
-  //        callbacks from asynchronous queries.
-  // Add MUs to the OutstandingMUs list.
-  {
-    std::lock_guard<std::recursive_mutex> Lock(ES.OutstandingMUsMutex);
-    auto ThisJD = shared_from_this();
-    for (auto &MU : MUs) {
-      auto MR = MU->createMaterializationResponsibility(ThisJD);
-      ES.OutstandingMUs.push_back(make_pair(std::move(MU), std::move(MR)));
-    }
-  }
-  ES.runOutstandingMUs();
-
-  // Dispatch any required MaterializationUnits for materialization.
-  // for (auto &MU : MUs)
-  //  ES.dispatchMaterialization(*this, std::move(MU));
-
-  SymbolNameSet RemainingSymbols;
-  for (auto &KV : Unresolved)
-    RemainingSymbols.insert(KV.first);
-
-  return RemainingSymbols;
-}
-
-bool JITDylib::lookupImpl(
-    std::shared_ptr<AsynchronousSymbolQuery> &Q,
-    std::vector<std::unique_ptr<MaterializationUnit>> &MUs,
-    SymbolLookupSet &Unresolved) {
-  bool QueryComplete = false;
-
-  std::vector<SymbolStringPtr> ToRemove;
-  Unresolved.forEachWithRemoval(
-      [&](const SymbolStringPtr &Name, SymbolLookupFlags Flags) -> bool {
-        // Search for the name in Symbols. Skip without removing if not found.
-        auto SymI = Symbols.find(Name);
-        if (SymI == Symbols.end())
-          return false;
-
-        // If the symbol is already in the required state then notify the query
-        // and remove.
-        if (SymI->second.getState() >= Q->getRequiredState()) {
-          Q->notifySymbolMetRequiredState(Name, SymI->second.getSymbol());
-          if (Q->isComplete())
-            QueryComplete = true;
-          return true;
-        }
-
-        // If the symbol is lazy, get the MaterialiaztionUnit for it.
-        if (SymI->second.hasMaterializerAttached()) {
-          assert(SymI->second.getAddress() == 0 &&
-                 "Lazy symbol should not have a resolved address");
-          auto UMII = UnmaterializedInfos.find(Name);
-          assert(UMII != UnmaterializedInfos.end() &&
-                 "Lazy symbol should have UnmaterializedInfo");
-          auto MU = std::move(UMII->second->MU);
-          assert(MU != nullptr && "Materializer should not be null");
-
-          // Kick all symbols associated with this MaterializationUnit into
-          // materializing state.
-          for (auto &KV : MU->getSymbols()) {
-            auto SymK = Symbols.find(KV.first);
-            assert(SymK != Symbols.end() && "Missing symbol table entry");
-            SymK->second.setState(SymbolState::Materializing);
-            SymK->second.setMaterializerAttached(false);
-            UnmaterializedInfos.erase(KV.first);
-          }
-
-          // Add MU to the list of MaterializationUnits to be materialized.
-          MUs.push_back(std::move(MU));
-        }
-
-        // Add the query to the PendingQueries list.
-        assert(SymI->second.getState() != SymbolState::NeverSearched &&
-               SymI->second.getState() != SymbolState::Ready &&
-               "By this line the symbol should be materializing");
-        auto &MI = MaterializingInfos[Name];
-        MI.addQuery(Q);
-        Q->addQueryDependence(*this, Name);
-        return true;
-      });
-
-  return QueryComplete;
-}
-
 void JITDylib::dump(raw_ostream &OS) {
   ES.runSessionLocked([&, this]() {
     OS << "JITDylib \"" << JITDylibName << "\" (ES: "
@@ -1589,11 +1391,10 @@ void JITDylib::MaterializingInfo::addQuery(
 void JITDylib::MaterializingInfo::removeQuery(
     const AsynchronousSymbolQuery &Q) {
   // FIXME: Implement 'find_as' for shared_ptr<T>/T*.
-  auto I =
-      std::find_if(PendingQueries.begin(), PendingQueries.end(),
-                   [&Q](const std::shared_ptr<AsynchronousSymbolQuery> &V) {
-                     return V.get() == &Q;
-                   });
+  auto I = llvm::find_if(
+      PendingQueries, [&Q](const std::shared_ptr<AsynchronousSymbolQuery> &V) {
+        return V.get() == &Q;
+      });
   assert(I != PendingQueries.end() &&
          "Query is not attached to this MaterializingInfo");
   PendingQueries.erase(I);
@@ -1618,6 +1419,137 @@ JITDylib::JITDylib(ExecutionSession &ES, std::string Name)
   LinkOrder.push_back({this, JITDylibLookupFlags::MatchAllSymbols});
 }
 
+ResourceTrackerSP JITDylib::getTracker(MaterializationResponsibility &MR) {
+  auto I = MRTrackers.find(&MR);
+  assert(I != MRTrackers.end() && "MR is not linked");
+  assert(I->second && "Linked tracker is null");
+  return I->second;
+}
+
+std::pair<JITDylib::AsynchronousSymbolQuerySet,
+          std::shared_ptr<SymbolDependenceMap>>
+JITDylib::removeTracker(ResourceTracker &RT) {
+  // Note: Should be called under the session lock.
+
+  SymbolNameVector SymbolsToRemove;
+  std::vector<std::pair<JITDylib *, SymbolStringPtr>> SymbolsToFail;
+
+  if (&RT == DefaultTracker.get()) {
+    SymbolNameSet TrackedSymbols;
+    for (auto &KV : TrackerSymbols)
+      for (auto &Sym : KV.second)
+        TrackedSymbols.insert(Sym);
+
+    for (auto &KV : Symbols) {
+      auto &Sym = KV.first;
+      if (!TrackedSymbols.count(Sym))
+        SymbolsToRemove.push_back(Sym);
+    }
+
+    DefaultTracker.reset();
+  } else {
+    /// Check for a non-default tracker.
+    auto I = TrackerSymbols.find(&RT);
+    if (I != TrackerSymbols.end()) {
+      SymbolsToRemove = std::move(I->second);
+      TrackerSymbols.erase(I);
+    }
+    // ... if not found this tracker was already defunct. Nothing to do.
+  }
+
+  for (auto &Sym : SymbolsToRemove) {
+    assert(Symbols.count(Sym) && "Symbol not in symbol table");
+
+    // If there is a MaterializingInfo then collect any queries to fail.
+    auto MII = MaterializingInfos.find(Sym);
+    if (MII != MaterializingInfos.end())
+      SymbolsToFail.push_back({this, Sym});
+  }
+
+  AsynchronousSymbolQuerySet QueriesToFail;
+  auto Result = failSymbols(std::move(SymbolsToFail));
+
+  // Removed symbols should be taken out of the table altogether.
+  for (auto &Sym : SymbolsToRemove) {
+    auto I = Symbols.find(Sym);
+    assert(I != Symbols.end() && "Symbol not present in table");
+
+    // Remove Materializer if present.
+    if (I->second.hasMaterializerAttached()) {
+      // FIXME: Should this discard the symbols?
+      UnmaterializedInfos.erase(Sym);
+    } else {
+      assert(!UnmaterializedInfos.count(Sym) &&
+             "Symbol has materializer attached");
+    }
+
+    Symbols.erase(I);
+  }
+
+  return Result;
+}
+
+void JITDylib::transferTracker(ResourceTracker &DstRT, ResourceTracker &SrcRT) {
+  assert(&DstRT != &SrcRT && "No-op transfers shouldn't call transferTracker");
+  assert(&DstRT.getJITDylib() == this && "DstRT is not for this JITDylib");
+  assert(&SrcRT.getJITDylib() == this && "SrcRT is not for this JITDylib");
+
+  // Update trackers for any not-yet materialized units.
+  for (auto &KV : UnmaterializedInfos) {
+    if (KV.second->RT == &SrcRT)
+      KV.second->RT = &DstRT;
+  }
+
+  // Update trackers for any active materialization responsibilities.
+  for (auto &KV : MRTrackers) {
+    if (KV.second == &SrcRT)
+      KV.second = &DstRT;
+  }
+
+  // If we're transfering to the default tracker we just need to delete the
+  // tracked symbols for the source tracker.
+  if (&DstRT == DefaultTracker.get()) {
+    TrackerSymbols.erase(&SrcRT);
+    return;
+  }
+
+  // If we're transferring from the default tracker we need to find all
+  // currently untracked symbols.
+  if (&SrcRT == DefaultTracker.get()) {
+    assert(!TrackerSymbols.count(&SrcRT) &&
+           "Default tracker should not appear in TrackerSymbols");
+
+    SymbolNameVector SymbolsToTrack;
+
+    SymbolNameSet CurrentlyTrackedSymbols;
+    for (auto &KV : TrackerSymbols)
+      for (auto &Sym : KV.second)
+        CurrentlyTrackedSymbols.insert(Sym);
+
+    for (auto &KV : Symbols) {
+      auto &Sym = KV.first;
+      if (!CurrentlyTrackedSymbols.count(Sym))
+        SymbolsToTrack.push_back(Sym);
+    }
+
+    TrackerSymbols[&DstRT] = std::move(SymbolsToTrack);
+    return;
+  }
+
+  auto &DstTrackedSymbols = TrackerSymbols[&DstRT];
+
+  // Finally if neither SrtRT or DstRT are the default tracker then
+  // just append DstRT's tracked symbols to SrtRT's.
+  auto SI = TrackerSymbols.find(&SrcRT);
+  if (SI == TrackerSymbols.end())
+    return;
+
+  DstTrackedSymbols.reserve(DstTrackedSymbols.size() + SI->second.size());
+  for (auto &Sym : SI->second)
+    DstTrackedSymbols.push_back(std::move(Sym));
+  TrackerSymbols.erase(SI);
+}
+
 Error JITDylib::defineImpl(MaterializationUnit &MU) {
 
   LLVM_DEBUG({ dbgs() << "  " << MU.getSymbols() << "\n"; });
@@ -1685,6 +1617,22 @@ Error JITDylib::defineImpl(MaterializationUnit &MU) {
   return Error::success();
 }
 
+void JITDylib::installMaterializationUnit(
+    std::unique_ptr<MaterializationUnit> MU, ResourceTracker &RT) {
+
+  /// defineImpl succeeded.
+  if (&RT != DefaultTracker.get()) {
+    auto &TS = TrackerSymbols[&RT];
+    TS.reserve(TS.size() + MU->getSymbols().size());
+    for (auto &KV : MU->getSymbols())
+      TS.push_back(KV.first);
+  }
+
+  auto UMI = std::make_shared<UnmaterializedInfo>(std::move(MU), &RT);
+  for (auto &KV : UMI->MU->getSymbols())
+    UnmaterializedInfos[KV.first] = UMI;
+}
+
 void JITDylib::detachQueryHelper(AsynchronousSymbolQuery &Q,
                                  const SymbolNameSet &QuerySymbols) {
   for (auto &QuerySymbol : QuerySymbols) {
@@ -1773,7 +1721,39 @@ Expected<DenseMap<JITDylib *, SymbolMap>> Platform::lookupInitSymbols(
 }
 
 ExecutionSession::ExecutionSession(std::shared_ptr<SymbolStringPool> SSP)
-    : SSP(SSP ? std::move(SSP) : std::make_shared<SymbolStringPool>()) {
+    : SSP(SSP ? std::move(SSP) : std::make_shared<SymbolStringPool>()) {}
+
+Error ExecutionSession::endSession() {
+  LLVM_DEBUG(dbgs() << "Ending ExecutionSession " << this << "\n");
+
+  std::vector<JITDylibSP> JITDylibsToClose = runSessionLocked([&] {
+    SessionOpen = false;
+    return std::move(JDs);
+  });
+
+  // TODO: notifiy platform? run static deinits?
+
+  Error Err = Error::success();
+  for (auto &JD : JITDylibsToClose)
+    Err = joinErrors(std::move(Err), JD->clear());
+  return Err;
+}
+
+void ExecutionSession::registerResourceManager(ResourceManager &RM) {
+  runSessionLocked([&] { ResourceManagers.push_back(&RM); });
+}
+
+void ExecutionSession::deregisterResourceManager(ResourceManager &RM) {
+  runSessionLocked([&] {
+    assert(!ResourceManagers.empty() && "No managers registered");
+    if (ResourceManagers.back() == &RM)
+      ResourceManagers.pop_back();
+    else {
+      auto I = llvm::find(ResourceManagers, &RM);
+      assert(I != ResourceManagers.end() && "RM not registered");
+      ResourceManagers.erase(I);
+    }
+  });
 }
 
 JITDylib *ExecutionSession::getJITDylibByName(StringRef Name) {
@@ -1788,8 +1768,7 @@ JITDylib *ExecutionSession::getJITDylibByName(StringRef Name) {
 JITDylib &ExecutionSession::createBareJITDylib(std::string Name) {
   assert(!getJITDylibByName(Name) && "JITDylib with that name already exists");
   return runSessionLocked([&, this]() -> JITDylib & {
-    JDs.push_back(
-        std::shared_ptr<JITDylib>(new JITDylib(*this, std::move(Name))));
+    JDs.push_back(new JITDylib(*this, std::move(Name)));
     return *JDs.back();
   });
 }
@@ -1802,86 +1781,80 @@ Expected<JITDylib &> ExecutionSession::createJITDylib(std::string Name) {
   return JD;
 }
 
-void ExecutionSession::legacyFailQuery(AsynchronousSymbolQuery &Q, Error Err) {
-  assert(!!Err && "Error should be in failure state");
+std::vector<JITDylibSP> JITDylib::getDFSLinkOrder(ArrayRef<JITDylibSP> JDs) {
+  if (JDs.empty())
+    return {};
 
-  bool SendErrorToQuery;
-  runSessionLocked([&]() {
-    Q.detach();
-    SendErrorToQuery = Q.canStillFail();
+  auto &ES = JDs.front()->getExecutionSession();
+  return ES.runSessionLocked([&]() {
+    DenseSet<JITDylib *> Visited;
+    std::vector<JITDylibSP> Result;
+
+    for (auto &JD : JDs) {
+
+      if (Visited.count(JD.get()))
+        continue;
+
+      SmallVector<JITDylibSP, 64> WorkStack;
+      WorkStack.push_back(JD);
+      Visited.insert(JD.get());
+
+      while (!WorkStack.empty()) {
+        Result.push_back(std::move(WorkStack.back()));
+        WorkStack.pop_back();
+
+        for (auto &KV : llvm::reverse(Result.back()->LinkOrder)) {
+          auto &JD = *KV.first;
+          if (Visited.count(&JD))
+            continue;
+          Visited.insert(&JD);
+          WorkStack.push_back(&JD);
+        }
+      }
+    }
+    return Result;
   });
+}
 
-  if (SendErrorToQuery)
-    Q.handleFailed(std::move(Err));
-  else
-    reportError(std::move(Err));
+std::vector<JITDylibSP>
+JITDylib::getReverseDFSLinkOrder(ArrayRef<JITDylibSP> JDs) {
+  auto Tmp = getDFSLinkOrder(JDs);
+  std::reverse(Tmp.begin(), Tmp.end());
+  return Tmp;
 }
 
-Expected<SymbolMap> ExecutionSession::legacyLookup(
-    LegacyAsyncLookupFunction AsyncLookup, SymbolNameSet Names,
-    SymbolState RequiredState,
-    RegisterDependenciesFunction RegisterDependencies) {
-#if LLVM_ENABLE_THREADS
-  // In the threaded case we use promises to return the results.
-  std::promise<SymbolMap> PromisedResult;
-  Error ResolutionError = Error::success();
-  auto NotifyComplete = [&](Expected<SymbolMap> R) {
-    if (R)
-      PromisedResult.set_value(std::move(*R));
-    else {
-      ErrorAsOutParameter _(&ResolutionError);
-      ResolutionError = R.takeError();
-      PromisedResult.set_value(SymbolMap());
-    }
-  };
-#else
-  SymbolMap Result;
-  Error ResolutionError = Error::success();
+std::vector<JITDylibSP> JITDylib::getDFSLinkOrder() {
+  return getDFSLinkOrder({this});
+}
 
-  auto NotifyComplete = [&](Expected<SymbolMap> R) {
-    ErrorAsOutParameter _(&ResolutionError);
-    if (R)
-      Result = std::move(*R);
-    else
-      ResolutionError = R.takeError();
-  };
-#endif
+std::vector<JITDylibSP> JITDylib::getReverseDFSLinkOrder() {
+  return getReverseDFSLinkOrder({this});
+}
 
-  auto Query = std::make_shared<AsynchronousSymbolQuery>(
-      SymbolLookupSet(Names), RequiredState, std::move(NotifyComplete));
-  // FIXME: This should be run session locked along with the registration code
-  // and error reporting below.
-  SymbolNameSet UnresolvedSymbols = AsyncLookup(Query, std::move(Names));
+void ExecutionSession::lookupFlags(
+    LookupKind K, JITDylibSearchOrder SearchOrder, SymbolLookupSet LookupSet,
+    unique_function<void(Expected<SymbolFlagsMap>)> OnComplete) {
 
-  // If the query was lodged successfully then register the dependencies,
-  // otherwise fail it with an error.
-  if (UnresolvedSymbols.empty())
-    RegisterDependencies(Query->QueryRegistrations);
-  else {
-    bool DeliverError = runSessionLocked([&]() {
-      Query->detach();
-      return Query->canStillFail();
-    });
-    auto Err = make_error<SymbolsNotFound>(std::move(UnresolvedSymbols));
-    if (DeliverError)
-      Query->handleFailed(std::move(Err));
-    else
-      reportError(std::move(Err));
-  }
+  OL_applyQueryPhase1(std::make_unique<InProgressLookupFlagsState>(
+                          K, std::move(SearchOrder), std::move(LookupSet),
+                          std::move(OnComplete)),
+                      Error::success());
+}
 
-#if LLVM_ENABLE_THREADS
-  auto ResultFuture = PromisedResult.get_future();
-  auto Result = ResultFuture.get();
-  if (ResolutionError)
-    return std::move(ResolutionError);
-  return std::move(Result);
+Expected<SymbolFlagsMap>
+ExecutionSession::lookupFlags(LookupKind K, JITDylibSearchOrder SearchOrder,
+                              SymbolLookupSet LookupSet) {
 
-#else
-  if (ResolutionError)
-    return std::move(ResolutionError);
+  std::promise<MSVCPExpected<SymbolFlagsMap>> ResultP;
+  OL_applyQueryPhase1(std::make_unique<InProgressLookupFlagsState>(
+                          K, std::move(SearchOrder), std::move(LookupSet),
+                          [&ResultP](Expected<SymbolFlagsMap> Result) {
+                            ResultP.set_value(std::move(Result));
+                          }),
+                      Error::success());
 
-  return Result;
-#endif
+  auto ResultF = ResultP.get_future();
+  return ResultF.get();
 }
 
 void ExecutionSession::lookup(
@@ -1900,94 +1873,17 @@ void ExecutionSession::lookup(
   // lookup can be re-entered recursively if running on a single thread. Run any
   // outstanding MUs in case this query depends on them, otherwise this lookup
   // will starve waiting for a result from an MU that is stuck in the queue.
-  runOutstandingMUs();
+  dispatchOutstandingMUs();
 
   auto Unresolved = std::move(Symbols);
-  std::map<JITDylib *, MaterializationUnitList> CollectedMUsMap;
   auto Q = std::make_shared<AsynchronousSymbolQuery>(Unresolved, RequiredState,
                                                      std::move(NotifyComplete));
-  bool QueryComplete = false;
-
-  auto LodgingErr = runSessionLocked([&]() -> Error {
-    auto LodgeQuery = [&]() -> Error {
-      for (auto &KV : SearchOrder) {
-        assert(KV.first && "JITDylibList entries must not be null");
-        assert(!CollectedMUsMap.count(KV.first) &&
-               "JITDylibList should not contain duplicate entries");
-
-        auto &JD = *KV.first;
-        auto JDLookupFlags = KV.second;
-        if (auto Err = JD.lodgeQuery(CollectedMUsMap[&JD], Q, K, JDLookupFlags,
-                                     Unresolved))
-          return Err;
-      }
 
-      // Strip any weakly referenced symbols that were not found.
-      Unresolved.forEachWithRemoval(
-          [&](const SymbolStringPtr &Name, SymbolLookupFlags Flags) {
-            if (Flags == SymbolLookupFlags::WeaklyReferencedSymbol) {
-              Q->dropSymbol(Name);
-              return true;
-            }
-            return false;
-          });
-
-      if (!Unresolved.empty())
-        return make_error<SymbolsNotFound>(Unresolved.getSymbolNames());
-
-      return Error::success();
-    };
-
-    if (auto Err = LodgeQuery()) {
-      // Query failed.
-
-      // Disconnect the query from its dependencies.
-      Q->detach();
-
-      // Replace the MUs.
-      for (auto &KV : CollectedMUsMap)
-        for (auto &MU : KV.second)
-          KV.first->replace(std::move(MU));
-
-      return Err;
-    }
-
-    // Query lodged successfully.
-
-    // Record whether this query is fully ready / resolved. We will use
-    // this to call handleFullyResolved/handleFullyReady outside the session
-    // lock.
-    QueryComplete = Q->isComplete();
-
-    // Call the register dependencies function.
-    if (RegisterDependencies && !Q->QueryRegistrations.empty())
-      RegisterDependencies(Q->QueryRegistrations);
-
-    return Error::success();
-  });
-
-  if (LodgingErr) {
-    Q->handleFailed(std::move(LodgingErr));
-    return;
-  }
-
-  if (QueryComplete)
-    Q->handleComplete();
+  auto IPLS = std::make_unique<InProgressFullLookupState>(
+      K, SearchOrder, std::move(Unresolved), RequiredState, std::move(Q),
+      std::move(RegisterDependencies));
 
-  // Move the MUs to the OutstandingMUs list, then materialize.
-  {
-    std::lock_guard<std::recursive_mutex> Lock(OutstandingMUsMutex);
-
-    for (auto &KV : CollectedMUsMap) {
-      auto JD = KV.first->shared_from_this();
-      for (auto &MU : KV.second) {
-        auto MR = MU->createMaterializationResponsibility(JD);
-        OutstandingMUs.push_back(std::make_pair(std::move(MU), std::move(MR)));
-      }
-    }
-  }
-
-  runOutstandingMUs();
+  OL_applyQueryPhase1(std::move(IPLS), Error::success());
 }
 
 Expected<SymbolMap>
@@ -2077,10 +1973,11 @@ void ExecutionSession::dump(raw_ostream &OS) {
   });
 }
 
-void ExecutionSession::runOutstandingMUs() {
+void ExecutionSession::dispatchOutstandingMUs() {
+  LLVM_DEBUG(dbgs() << "Dispatching MaterializationUnits...\n");
   while (1) {
     Optional<std::pair<std::unique_ptr<MaterializationUnit>,
-                       MaterializationResponsibility>>
+                       std::unique_ptr<MaterializationResponsibility>>>
         JMU;
 
     {
@@ -2095,8 +1992,777 @@ void ExecutionSession::runOutstandingMUs() {
       break;
 
     assert(JMU->first && "No MU?");
+    LLVM_DEBUG(dbgs() << "  Dispatching \"" << JMU->first->getName() << "\"\n");
     dispatchMaterialization(std::move(JMU->first), std::move(JMU->second));
   }
+  LLVM_DEBUG(dbgs() << "Done dispatching MaterializationUnits.\n");
+}
+
+Error ExecutionSession::removeResourceTracker(ResourceTracker &RT) {
+  LLVM_DEBUG({
+    dbgs() << "In " << RT.getJITDylib().getName() << " removing tracker "
+           << formatv("{0:x}", RT.getKeyUnsafe()) << "\n";
+  });
+  std::vector<ResourceManager *> CurrentResourceManagers;
+
+  JITDylib::AsynchronousSymbolQuerySet QueriesToFail;
+  std::shared_ptr<SymbolDependenceMap> FailedSymbols;
+
+  runSessionLocked([&] {
+    CurrentResourceManagers = ResourceManagers;
+    RT.makeDefunct();
+    std::tie(QueriesToFail, FailedSymbols) = RT.getJITDylib().removeTracker(RT);
+  });
+
+  Error Err = Error::success();
+
+  for (auto *L : reverse(CurrentResourceManagers))
+    Err =
+        joinErrors(std::move(Err), L->handleRemoveResources(RT.getKeyUnsafe()));
+
+  for (auto &Q : QueriesToFail)
+    Q->handleFailed(make_error<FailedToMaterialize>(FailedSymbols));
+
+  return Err;
+}
+
+void ExecutionSession::transferResourceTracker(ResourceTracker &DstRT,
+                                               ResourceTracker &SrcRT) {
+  LLVM_DEBUG({
+    dbgs() << "In " << SrcRT.getJITDylib().getName()
+           << " transfering resources from tracker "
+           << formatv("{0:x}", SrcRT.getKeyUnsafe()) << " to tracker "
+           << formatv("{0:x}", DstRT.getKeyUnsafe()) << "\n";
+  });
+
+  // No-op transfers are allowed and do not invalidate the source.
+  if (&DstRT == &SrcRT)
+    return;
+
+  assert(&DstRT.getJITDylib() == &SrcRT.getJITDylib() &&
+         "Can't transfer resources between JITDylibs");
+  runSessionLocked([&]() {
+    SrcRT.makeDefunct();
+    auto &JD = DstRT.getJITDylib();
+    JD.transferTracker(DstRT, SrcRT);
+    for (auto *L : reverse(ResourceManagers))
+      L->handleTransferResources(DstRT.getKeyUnsafe(), SrcRT.getKeyUnsafe());
+  });
+}
+
+void ExecutionSession::destroyResourceTracker(ResourceTracker &RT) {
+  runSessionLocked([&]() {
+    LLVM_DEBUG({
+      dbgs() << "In " << RT.getJITDylib().getName() << " destroying tracker "
+             << formatv("{0:x}", RT.getKeyUnsafe()) << "\n";
+    });
+    if (!RT.isDefunct())
+      transferResourceTracker(*RT.getJITDylib().getDefaultResourceTracker(),
+                              RT);
+  });
+}
+
+Error ExecutionSession::IL_updateCandidatesFor(
+    JITDylib &JD, JITDylibLookupFlags JDLookupFlags,
+    SymbolLookupSet &Candidates, SymbolLookupSet *NonCandidates) {
+  return Candidates.forEachWithRemoval(
+      [&](const SymbolStringPtr &Name,
+          SymbolLookupFlags SymLookupFlags) -> Expected<bool> {
+        /// Search for the symbol. If not found then continue without
+        /// removal.
+        auto SymI = JD.Symbols.find(Name);
+        if (SymI == JD.Symbols.end())
+          return false;
+
+        // If this is a non-exported symbol and we're matching exported
+        // symbols only then remove this symbol from the candidates list.
+        //
+        // If we're tracking non-candidates then add this to the non-candidate
+        // list.
+        if (!SymI->second.getFlags().isExported() &&
+            JDLookupFlags == JITDylibLookupFlags::MatchExportedSymbolsOnly) {
+          if (NonCandidates)
+            NonCandidates->add(Name, SymLookupFlags);
+          return true;
+        }
+
+        // If we match against a materialization-side-effects only symbol
+        // then make sure it is weakly-referenced. Otherwise bail out with
+        // an error.
+        // FIXME: Use a "materialization-side-effects-only symbols must be
+        // weakly referenced" specific error here to reduce confusion.
+        if (SymI->second.getFlags().hasMaterializationSideEffectsOnly() &&
+            SymLookupFlags != SymbolLookupFlags::WeaklyReferencedSymbol)
+          return make_error<SymbolsNotFound>(SymbolNameVector({Name}));
+
+        // If we matched against this symbol but it is in the error state
+        // then bail out and treat it as a failure to materialize.
+        if (SymI->second.getFlags().hasError()) {
+          auto FailedSymbolsMap = std::make_shared<SymbolDependenceMap>();
+          (*FailedSymbolsMap)[&JD] = {Name};
+          return make_error<FailedToMaterialize>(std::move(FailedSymbolsMap));
+        }
+
+        // Otherwise this is a match. Remove it from the candidate set.
+        return true;
+      });
+}
+
+void ExecutionSession::OL_applyQueryPhase1(
+    std::unique_ptr<InProgressLookupState> IPLS, Error Err) {
+
+  LLVM_DEBUG({
+    dbgs() << "Entering OL_applyQueryPhase1:\n"
+           << "  Lookup kind: " << IPLS->K << "\n"
+           << "  Search order: " << IPLS->SearchOrder
+           << ", Current index = " << IPLS->CurSearchOrderIndex
+           << (IPLS->NewJITDylib ? " (entering new JITDylib)" : "") << "\n"
+           << "  Lookup set: " << IPLS->LookupSet << "\n"
+           << "  Definition generator candidates: "
+           << IPLS->DefGeneratorCandidates << "\n"
+           << "  Definition generator non-candidates: "
+           << IPLS->DefGeneratorNonCandidates << "\n";
+  });
+
+  // FIXME: We should attach the query as we go: This provides a result in a
+  // single pass in the common case where all symbols have already reached the
+  // required state. The query could be detached again in the 'fail' method on
+  // IPLS. Phase 2 would be reduced to collecting and dispatching the MUs.
+
+  while (IPLS->CurSearchOrderIndex != IPLS->SearchOrder.size()) {
+
+    // If we've been handed an error or received one back from a generator then
+    // fail the query. We don't need to unlink: At this stage the query hasn't
+    // actually been lodged.
+    if (Err)
+      return IPLS->fail(std::move(Err));
+
+    // Get the next JITDylib and lookup flags.
+    auto &KV = IPLS->SearchOrder[IPLS->CurSearchOrderIndex];
+    auto &JD = *KV.first;
+    auto JDLookupFlags = KV.second;
+
+    LLVM_DEBUG({
+      dbgs() << "Visiting \"" << JD.getName() << "\" (" << JDLookupFlags
+             << ") with lookup set " << IPLS->LookupSet << ":\n";
+    });
+
+    // If we've just reached a new JITDylib then perform some setup.
+    if (IPLS->NewJITDylib) {
+
+      // Acquire the generator lock for this JITDylib.
+      IPLS->GeneratorLock = std::unique_lock<std::mutex>(JD.GeneratorsMutex);
+
+      // Add any non-candidates from the last JITDylib (if any) back on to the
+      // list of definition candidates for this JITDylib, reset definition
+      // non-candiates to the empty set.
+      SymbolLookupSet Tmp;
+      std::swap(IPLS->DefGeneratorNonCandidates, Tmp);
+      IPLS->DefGeneratorCandidates.append(std::move(Tmp));
+
+      LLVM_DEBUG({
+        dbgs() << "  First time visiting " << JD.getName()
+               << ", resetting candidate sets and building generator stack\n";
+      });
+
+      // Build the definition generator stack for this JITDylib.
+      for (auto &DG : reverse(JD.DefGenerators))
+        IPLS->CurDefGeneratorStack.push_back(DG);
+
+      // Flag that we've done our initialization.
+      IPLS->NewJITDylib = false;
+    }
+
+    // Remove any generation candidates that are already defined (and match) in
+    // this JITDylib.
+    runSessionLocked([&] {
+      // Update the list of candidates (and non-candidates) for definition
+      // generation.
+      LLVM_DEBUG(dbgs() << "  Updating candidate set...\n");
+      Err = IL_updateCandidatesFor(
+          JD, JDLookupFlags, IPLS->DefGeneratorCandidates,
+          JD.DefGenerators.empty() ? nullptr
+                                   : &IPLS->DefGeneratorNonCandidates);
+      LLVM_DEBUG({
+        dbgs() << "    Remaining candidates = " << IPLS->DefGeneratorCandidates
+               << "\n";
+      });
+    });
+
+    // If we encountered an error while filtering generation candidates then
+    // bail out.
+    if (Err)
+      return IPLS->fail(std::move(Err));
+
+    /// Apply any definition generators on the stack.
+    LLVM_DEBUG({
+      if (IPLS->CurDefGeneratorStack.empty())
+        LLVM_DEBUG(dbgs() << "  No generators to run for this JITDylib.\n");
+      else if (IPLS->DefGeneratorCandidates.empty())
+        LLVM_DEBUG(dbgs() << "  No candidates to generate.\n");
+      else
+        dbgs() << "  Running " << IPLS->CurDefGeneratorStack.size()
+               << " remaining generators for "
+               << IPLS->DefGeneratorCandidates.size() << " candidates\n";
+    });
+    while (!IPLS->CurDefGeneratorStack.empty() &&
+           !IPLS->DefGeneratorCandidates.empty()) {
+      auto DG = IPLS->CurDefGeneratorStack.back().lock();
+      IPLS->CurDefGeneratorStack.pop_back();
+
+      if (!DG)
+        return IPLS->fail(make_error<StringError>(
+            "DefinitionGenerator removed while lookup in progress",
+            inconvertibleErrorCode()));
+
+      auto K = IPLS->K;
+      auto &LookupSet = IPLS->DefGeneratorCandidates;
+
+      // Run the generator. If the generator takes ownership of QA then this
+      // will break the loop.
+      {
+        LLVM_DEBUG(dbgs() << "  Attempting to generate " << LookupSet << "\n");
+        LookupState LS(std::move(IPLS));
+        Err = DG->tryToGenerate(LS, K, JD, JDLookupFlags, LookupSet);
+        IPLS = std::move(LS.IPLS);
+      }
+
+      // If there was an error then fail the query.
+      if (Err) {
+        LLVM_DEBUG({
+          dbgs() << "  Error attempting to generate " << LookupSet << "\n";
+        });
+        assert(IPLS && "LS cannot be retained if error is returned");
+        return IPLS->fail(std::move(Err));
+      }
+
+      // Otherwise if QA was captured then break the loop.
+      if (!IPLS) {
+        LLVM_DEBUG(
+            { dbgs() << "  LookupState captured. Exiting phase1 for now.\n"; });
+        return;
+      }
+
+      // Otherwise if we're continuing around the loop then update candidates
+      // for the next round.
+      runSessionLocked([&] {
+        LLVM_DEBUG(dbgs() << "  Updating candidate set post-generation\n");
+        Err = IL_updateCandidatesFor(
+            JD, JDLookupFlags, IPLS->DefGeneratorCandidates,
+            JD.DefGenerators.empty() ? nullptr
+                                     : &IPLS->DefGeneratorNonCandidates);
+      });
+
+      // If updating candidates failed then fail the query.
+      if (Err) {
+        LLVM_DEBUG(dbgs() << "  Error encountered while updating candidates\n");
+        return IPLS->fail(std::move(Err));
+      }
+    }
+
+    // If we get here then we've moved on to the next JITDylib.
+    LLVM_DEBUG(dbgs() << "Phase 1 moving to next JITDylib.\n");
+    ++IPLS->CurSearchOrderIndex;
+    IPLS->NewJITDylib = true;
+  }
+
+  // Remove any weakly referenced candidates that could not be found/generated.
+  IPLS->DefGeneratorCandidates.remove_if(
+      [](const SymbolStringPtr &Name, SymbolLookupFlags SymLookupFlags) {
+        return SymLookupFlags == SymbolLookupFlags::WeaklyReferencedSymbol;
+      });
+
+  // If we get here then we've finished searching all JITDylibs.
+  // If we matched all symbols then move to phase 2, otherwise fail the query
+  // with a SymbolsNotFound error.
+  if (IPLS->DefGeneratorCandidates.empty()) {
+    LLVM_DEBUG(dbgs() << "Phase 1 succeeded.\n");
+    IPLS->complete(std::move(IPLS));
+  } else {
+    LLVM_DEBUG(dbgs() << "Phase 1 failed with unresolved symbols.\n");
+    IPLS->fail(make_error<SymbolsNotFound>(
+        IPLS->DefGeneratorCandidates.getSymbolNames()));
+  }
+}
+
+void ExecutionSession::OL_completeLookup(
+    std::unique_ptr<InProgressLookupState> IPLS,
+    std::shared_ptr<AsynchronousSymbolQuery> Q,
+    RegisterDependenciesFunction RegisterDependencies) {
+
+  LLVM_DEBUG({
+    dbgs() << "Entering OL_completeLookup:\n"
+           << "  Lookup kind: " << IPLS->K << "\n"
+           << "  Search order: " << IPLS->SearchOrder
+           << ", Current index = " << IPLS->CurSearchOrderIndex
+           << (IPLS->NewJITDylib ? " (entering new JITDylib)" : "") << "\n"
+           << "  Lookup set: " << IPLS->LookupSet << "\n"
+           << "  Definition generator candidates: "
+           << IPLS->DefGeneratorCandidates << "\n"
+           << "  Definition generator non-candidates: "
+           << IPLS->DefGeneratorNonCandidates << "\n";
+  });
+
+  bool QueryComplete = false;
+  DenseMap<JITDylib *, JITDylib::UnmaterializedInfosList> CollectedUMIs;
+
+  auto LodgingErr = runSessionLocked([&]() -> Error {
+    for (auto &KV : IPLS->SearchOrder) {
+      auto &JD = *KV.first;
+      auto JDLookupFlags = KV.second;
+      LLVM_DEBUG({
+        dbgs() << "Visiting \"" << JD.getName() << "\" (" << JDLookupFlags
+               << ") with lookup set " << IPLS->LookupSet << ":\n";
+      });
+
+      auto Err = IPLS->LookupSet.forEachWithRemoval(
+          [&](const SymbolStringPtr &Name,
+              SymbolLookupFlags SymLookupFlags) -> Expected<bool> {
+            LLVM_DEBUG({
+              dbgs() << "  Attempting to match \"" << Name << "\" ("
+                     << SymLookupFlags << ")... ";
+            });
+
+            /// Search for the symbol. If not found then continue without
+            /// removal.
+            auto SymI = JD.Symbols.find(Name);
+            if (SymI == JD.Symbols.end()) {
+              LLVM_DEBUG(dbgs() << "skipping: not present\n");
+              return false;
+            }
+
+            // If this is a non-exported symbol and we're matching exported
+            // symbols only then skip this symbol without removal.
+            if (!SymI->second.getFlags().isExported() &&
+                JDLookupFlags ==
+                    JITDylibLookupFlags::MatchExportedSymbolsOnly) {
+              LLVM_DEBUG(dbgs() << "skipping: not exported\n");
+              return false;
+            }
+
+            // If we match against a materialization-side-effects only symbol
+            // then make sure it is weakly-referenced. Otherwise bail out with
+            // an error.
+            // FIXME: Use a "materialization-side-effects-only symbols must be
+            // weakly referenced" specific error here to reduce confusion.
+            if (SymI->second.getFlags().hasMaterializationSideEffectsOnly() &&
+                SymLookupFlags != SymbolLookupFlags::WeaklyReferencedSymbol) {
+              LLVM_DEBUG({
+                dbgs() << "error: "
+                          "required, but symbol is has-side-effects-only\n";
+              });
+              return make_error<SymbolsNotFound>(SymbolNameVector({Name}));
+            }
+
+            // If we matched against this symbol but it is in the error state
+            // then bail out and treat it as a failure to materialize.
+            if (SymI->second.getFlags().hasError()) {
+              LLVM_DEBUG(dbgs() << "error: symbol is in error state\n");
+              auto FailedSymbolsMap = std::make_shared<SymbolDependenceMap>();
+              (*FailedSymbolsMap)[&JD] = {Name};
+              return make_error<FailedToMaterialize>(
+                  std::move(FailedSymbolsMap));
+            }
+
+            // Otherwise this is a match.
+
+            // If this symbol is already in the requried state then notify the
+            // query, remove the symbol and continue.
+            if (SymI->second.getState() >= Q->getRequiredState()) {
+              LLVM_DEBUG(dbgs()
+                         << "matched, symbol already in required state\n");
+              Q->notifySymbolMetRequiredState(Name, SymI->second.getSymbol());
+              return true;
+            }
+
+            // Otherwise this symbol does not yet meet the required state. Check
+            // whether it has a materializer attached, and if so prepare to run
+            // it.
+            if (SymI->second.hasMaterializerAttached()) {
+              assert(SymI->second.getAddress() == 0 &&
+                     "Symbol not resolved but already has address?");
+              auto UMII = JD.UnmaterializedInfos.find(Name);
+              assert(UMII != JD.UnmaterializedInfos.end() &&
+                     "Lazy symbol should have UnmaterializedInfo");
+
+              auto UMI = UMII->second;
+              assert(UMI->MU && "Materializer should not be null");
+              assert(UMI->RT && "Tracker should not be null");
+              LLVM_DEBUG({
+                dbgs() << "matched, preparing to dispatch MU@" << UMI->MU.get()
+                       << " (" << UMI->MU->getName() << ")\n";
+              });
+
+              // Move all symbols associated with this MaterializationUnit into
+              // materializing state.
+              for (auto &KV : UMI->MU->getSymbols()) {
+                auto SymK = JD.Symbols.find(KV.first);
+                assert(SymK != JD.Symbols.end() &&
+                       "No entry for symbol covered by MaterializationUnit");
+                SymK->second.setMaterializerAttached(false);
+                SymK->second.setState(SymbolState::Materializing);
+                JD.UnmaterializedInfos.erase(KV.first);
+              }
+
+              // Add MU to the list of MaterializationUnits to be materialized.
+              CollectedUMIs[&JD].push_back(std::move(UMI));
+            } else
+              LLVM_DEBUG(dbgs() << "matched, registering query");
+
+            // Add the query to the PendingQueries list and continue, deleting
+            // the element from the lookup set.
+            assert(SymI->second.getState() != SymbolState::NeverSearched &&
+                   SymI->second.getState() != SymbolState::Ready &&
+                   "By this line the symbol should be materializing");
+            auto &MI = JD.MaterializingInfos[Name];
+            MI.addQuery(Q);
+            Q->addQueryDependence(JD, Name);
+
+            return true;
+          });
+
+      // Handle failure.
+      if (Err) {
+
+        LLVM_DEBUG({
+          dbgs() << "Lookup failed. Detaching query and replacing MUs.\n";
+        });
+
+        // Detach the query.
+        Q->detach();
+
+        // Replace the MUs.
+        for (auto &KV : CollectedUMIs) {
+          auto &JD = *KV.first;
+          for (auto &UMI : KV.second)
+            for (auto &KV2 : UMI->MU->getSymbols()) {
+              assert(!JD.UnmaterializedInfos.count(KV2.first) &&
+                     "Unexpected materializer in map");
+              auto SymI = JD.Symbols.find(KV2.first);
+              assert(SymI != JD.Symbols.end() && "Missing symbol entry");
+              assert(SymI->second.getState() == SymbolState::Materializing &&
+                     "Can not replace symbol that is not materializing");
+              assert(!SymI->second.hasMaterializerAttached() &&
+                     "MaterializerAttached flag should not be set");
+              SymI->second.setMaterializerAttached(true);
+              JD.UnmaterializedInfos[KV2.first] = UMI;
+            }
+        }
+
+        return Err;
+      }
+    }
+
+    LLVM_DEBUG(dbgs() << "Stripping unmatched weakly-refererced symbols\n");
+    IPLS->LookupSet.forEachWithRemoval(
+        [&](const SymbolStringPtr &Name, SymbolLookupFlags SymLookupFlags) {
+          if (SymLookupFlags == SymbolLookupFlags::WeaklyReferencedSymbol) {
+            Q->dropSymbol(Name);
+            return true;
+          } else
+            return false;
+        });
+
+    if (!IPLS->LookupSet.empty()) {
+      LLVM_DEBUG(dbgs() << "Failing due to unresolved symbols\n");
+      return make_error<SymbolsNotFound>(IPLS->LookupSet.getSymbolNames());
+    }
+
+    // Record whether the query completed.
+    QueryComplete = Q->isComplete();
+
+    LLVM_DEBUG({
+      dbgs() << "Query successfully "
+             << (QueryComplete ? "completed" : "lodged") << "\n";
+    });
+
+    // Move the collected MUs to the OutstandingMUs list.
+    if (!CollectedUMIs.empty()) {
+      std::lock_guard<std::recursive_mutex> Lock(OutstandingMUsMutex);
+
+      LLVM_DEBUG(dbgs() << "Adding MUs to dispatch:\n");
+      for (auto &KV : CollectedUMIs) {
+        auto &JD = *KV.first;
+        LLVM_DEBUG({
+          dbgs() << "  For " << JD.getName() << ": Adding " << KV.second.size()
+                 << " MUs.\n";
+        });
+        for (auto &UMI : KV.second) {
+          std::unique_ptr<MaterializationResponsibility> MR(
+              new MaterializationResponsibility(
+                  &JD, std::move(UMI->MU->SymbolFlags),
+                  std::move(UMI->MU->InitSymbol)));
+          JD.MRTrackers[MR.get()] = UMI->RT;
+          OutstandingMUs.push_back(
+              std::make_pair(std::move(UMI->MU), std::move(MR)));
+        }
+      }
+    } else
+      LLVM_DEBUG(dbgs() << "No MUs to dispatch.\n");
+
+    if (RegisterDependencies && !Q->QueryRegistrations.empty()) {
+      LLVM_DEBUG(dbgs() << "Registering dependencies\n");
+      RegisterDependencies(Q->QueryRegistrations);
+    } else
+      LLVM_DEBUG(dbgs() << "No dependencies to register\n");
+
+    return Error::success();
+  });
+
+  if (LodgingErr) {
+    LLVM_DEBUG(dbgs() << "Failing query\n");
+    Q->detach();
+    Q->handleFailed(std::move(LodgingErr));
+    return;
+  }
+
+  if (QueryComplete) {
+    LLVM_DEBUG(dbgs() << "Completing query\n");
+    Q->handleComplete();
+  }
+
+  dispatchOutstandingMUs();
+}
+
+void ExecutionSession::OL_completeLookupFlags(
+    std::unique_ptr<InProgressLookupState> IPLS,
+    unique_function<void(Expected<SymbolFlagsMap>)> OnComplete) {
+
+  auto Result = runSessionLocked([&]() -> Expected<SymbolFlagsMap> {
+    LLVM_DEBUG({
+      dbgs() << "Entering OL_completeLookupFlags:\n"
+             << "  Lookup kind: " << IPLS->K << "\n"
+             << "  Search order: " << IPLS->SearchOrder
+             << ", Current index = " << IPLS->CurSearchOrderIndex
+             << (IPLS->NewJITDylib ? " (entering new JITDylib)" : "") << "\n"
+             << "  Lookup set: " << IPLS->LookupSet << "\n"
+             << "  Definition generator candidates: "
+             << IPLS->DefGeneratorCandidates << "\n"
+             << "  Definition generator non-candidates: "
+             << IPLS->DefGeneratorNonCandidates << "\n";
+    });
+
+    SymbolFlagsMap Result;
+
+    // Attempt to find flags for each symbol.
+    for (auto &KV : IPLS->SearchOrder) {
+      auto &JD = *KV.first;
+      auto JDLookupFlags = KV.second;
+      LLVM_DEBUG({
+        dbgs() << "Visiting \"" << JD.getName() << "\" (" << JDLookupFlags
+               << ") with lookup set " << IPLS->LookupSet << ":\n";
+      });
+
+      IPLS->LookupSet.forEachWithRemoval([&](const SymbolStringPtr &Name,
+                                             SymbolLookupFlags SymLookupFlags) {
+        LLVM_DEBUG({
+          dbgs() << "  Attempting to match \"" << Name << "\" ("
+                 << SymLookupFlags << ")... ";
+        });
+
+        // Search for the symbol. If not found then continue without removing
+        // from the lookup set.
+        auto SymI = JD.Symbols.find(Name);
+        if (SymI == JD.Symbols.end()) {
+          LLVM_DEBUG(dbgs() << "skipping: not present\n");
+          return false;
+        }
+
+        // If this is a non-exported symbol then it doesn't match. Skip it.
+        if (!SymI->second.getFlags().isExported() &&
+            JDLookupFlags == JITDylibLookupFlags::MatchExportedSymbolsOnly) {
+          LLVM_DEBUG(dbgs() << "skipping: not exported\n");
+          return false;
+        }
+
+        LLVM_DEBUG({
+          dbgs() << "matched, \"" << Name << "\" -> " << SymI->second.getFlags()
+                 << "\n";
+        });
+        Result[Name] = SymI->second.getFlags();
+        return true;
+      });
+    }
+
+    // Remove any weakly referenced symbols that haven't been resolved.
+    IPLS->LookupSet.remove_if(
+        [](const SymbolStringPtr &Name, SymbolLookupFlags SymLookupFlags) {
+          return SymLookupFlags == SymbolLookupFlags::WeaklyReferencedSymbol;
+        });
+
+    if (!IPLS->LookupSet.empty()) {
+      LLVM_DEBUG(dbgs() << "Failing due to unresolved symbols\n");
+      return make_error<SymbolsNotFound>(IPLS->LookupSet.getSymbolNames());
+    }
+
+    LLVM_DEBUG(dbgs() << "Succeded, result = " << Result << "\n");
+    return Result;
+  });
+
+  // Run the callback on the result.
+  LLVM_DEBUG(dbgs() << "Sending result to handler.\n");
+  OnComplete(std::move(Result));
+}
+
+void ExecutionSession::OL_destroyMaterializationResponsibility(
+    MaterializationResponsibility &MR) {
+
+  assert(MR.SymbolFlags.empty() &&
+         "All symbols should have been explicitly materialized or failed");
+  MR.JD->unlinkMaterializationResponsibility(MR);
+}
+
+SymbolNameSet ExecutionSession::OL_getRequestedSymbols(
+    const MaterializationResponsibility &MR) {
+  return MR.JD->getRequestedSymbols(MR.SymbolFlags);
+}
+
+Error ExecutionSession::OL_notifyResolved(MaterializationResponsibility &MR,
+                                          const SymbolMap &Symbols) {
+  LLVM_DEBUG({
+    dbgs() << "In " << MR.JD->getName() << " resolving " << Symbols << "\n";
+  });
+#ifndef NDEBUG
+  for (auto &KV : Symbols) {
+    auto WeakFlags = JITSymbolFlags::Weak | JITSymbolFlags::Common;
+    auto I = MR.SymbolFlags.find(KV.first);
+    assert(I != MR.SymbolFlags.end() &&
+           "Resolving symbol outside this responsibility set");
+    assert(!I->second.hasMaterializationSideEffectsOnly() &&
+           "Can't resolve materialization-side-effects-only symbol");
+    assert((KV.second.getFlags() & ~WeakFlags) == (I->second & ~WeakFlags) &&
+           "Resolving symbol with incorrect flags");
+  }
+#endif
+
+  return MR.JD->resolve(MR, Symbols);
+}
+
+Error ExecutionSession::OL_notifyEmitted(MaterializationResponsibility &MR) {
+  LLVM_DEBUG({
+    dbgs() << "In " << MR.JD->getName() << " emitting " << MR.SymbolFlags << "\n";
+  });
+
+  if (auto Err = MR.JD->emit(MR, MR.SymbolFlags))
+    return Err;
+
+  MR.SymbolFlags.clear();
+  return Error::success();
+}
+
+Error ExecutionSession::OL_defineMaterializing(
+    MaterializationResponsibility &MR, SymbolFlagsMap NewSymbolFlags) {
+
+  LLVM_DEBUG({
+    dbgs() << "In " << MR.JD->getName() << " defining materializing symbols "
+           << NewSymbolFlags << "\n";
+  });
+  if (auto AcceptedDefs = MR.JD->defineMaterializing(std::move(NewSymbolFlags))) {
+    // Add all newly accepted symbols to this responsibility object.
+    for (auto &KV : *AcceptedDefs)
+      MR.SymbolFlags.insert(KV);
+    return Error::success();
+  } else
+    return AcceptedDefs.takeError();
+}
+
+void ExecutionSession::OL_notifyFailed(MaterializationResponsibility &MR) {
+
+  LLVM_DEBUG({
+    dbgs() << "In " << MR.JD->getName() << " failing materialization for "
+           << MR.SymbolFlags << "\n";
+  });
+
+  JITDylib::FailedSymbolsWorklist Worklist;
+
+  for (auto &KV : MR.SymbolFlags)
+    Worklist.push_back(std::make_pair(MR.JD.get(), KV.first));
+  MR.SymbolFlags.clear();
+
+  if (Worklist.empty())
+    return;
+
+  JITDylib::AsynchronousSymbolQuerySet FailedQueries;
+  std::shared_ptr<SymbolDependenceMap> FailedSymbols;
+
+  runSessionLocked([&]() {
+    auto RTI = MR.JD->MRTrackers.find(&MR);
+    assert(RTI != MR.JD->MRTrackers.end() && "No tracker for this");
+    if (RTI->second->isDefunct())
+      return;
+
+    std::tie(FailedQueries, FailedSymbols) =
+        JITDylib::failSymbols(std::move(Worklist));
+  });
+
+  for (auto &Q : FailedQueries)
+    Q->handleFailed(make_error<FailedToMaterialize>(FailedSymbols));
+}
+
+Error ExecutionSession::OL_replace(MaterializationResponsibility &MR,
+                                   std::unique_ptr<MaterializationUnit> MU) {
+  for (auto &KV : MU->getSymbols()) {
+    assert(MR.SymbolFlags.count(KV.first) &&
+           "Replacing definition outside this responsibility set");
+    MR.SymbolFlags.erase(KV.first);
+  }
+
+  if (MU->getInitializerSymbol() == MR.InitSymbol)
+    MR.InitSymbol = nullptr;
+
+  LLVM_DEBUG(MR.JD->getExecutionSession().runSessionLocked([&]() {
+    dbgs() << "In " << MR.JD->getName() << " replacing symbols with " << *MU
+           << "\n";
+  }););
+
+  return MR.JD->replace(MR, std::move(MU));
+}
+
+Expected<std::unique_ptr<MaterializationResponsibility>>
+ExecutionSession::OL_delegate(MaterializationResponsibility &MR,
+                              const SymbolNameSet &Symbols) {
+
+  SymbolStringPtr DelegatedInitSymbol;
+  SymbolFlagsMap DelegatedFlags;
+
+  for (auto &Name : Symbols) {
+    auto I = MR.SymbolFlags.find(Name);
+    assert(I != MR.SymbolFlags.end() &&
+           "Symbol is not tracked by this MaterializationResponsibility "
+           "instance");
+
+    DelegatedFlags[Name] = std::move(I->second);
+    if (Name == MR.InitSymbol)
+      std::swap(MR.InitSymbol, DelegatedInitSymbol);
+
+    MR.SymbolFlags.erase(I);
+  }
+
+  return MR.JD->delegate(MR, std::move(DelegatedFlags),
+                         std::move(DelegatedInitSymbol));
+}
+
+void ExecutionSession::OL_addDependencies(
+    MaterializationResponsibility &MR, const SymbolStringPtr &Name,
+    const SymbolDependenceMap &Dependencies) {
+  LLVM_DEBUG({
+    dbgs() << "Adding dependencies for " << Name << ": " << Dependencies
+           << "\n";
+  });
+  assert(MR.SymbolFlags.count(Name) &&
+         "Symbol not covered by this MaterializationResponsibility instance");
+  MR.JD->addDependencies(Name, Dependencies);
+}
+
+void ExecutionSession::OL_addDependenciesForAll(
+    MaterializationResponsibility &MR,
+    const SymbolDependenceMap &Dependencies) {
+  LLVM_DEBUG({
+    dbgs() << "Adding dependencies for all symbols in " << MR.SymbolFlags << ": "
+           << Dependencies << "\n";
+  });
+  for (auto &KV : MR.SymbolFlags)
+    MR.JD->addDependencies(KV.first, Dependencies);
 }
 
 #ifndef NDEBUG
diff --git a/llvm/lib/ExecutionEngine/Orc/ExecutionUtils.cpp b/llvm/lib/ExecutionEngine/Orc/ExecutionUtils.cpp
index 4d255cd66c1b..6a1a41a13a1b 100644
--- a/llvm/lib/ExecutionEngine/Orc/ExecutionUtils.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/ExecutionUtils.cpp
@@ -21,32 +21,6 @@
 namespace llvm {
 namespace orc {
 
-int runAsMain(int (*Main)(int, char *[]), ArrayRef<std::string> Args,
-              Optional<StringRef> ProgramName) {
-  std::vector<std::unique_ptr<char[]>> ArgVStorage;
-  std::vector<char *> ArgV;
-
-  ArgVStorage.reserve(Args.size() + (ProgramName ? 1 : 0));
-  ArgV.reserve(Args.size() + 1 + (ProgramName ? 1 : 0));
-
-  if (ProgramName) {
-    ArgVStorage.push_back(std::make_unique<char[]>(ProgramName->size() + 1));
-    llvm::copy(*ProgramName, &ArgVStorage.back()[0]);
-    ArgVStorage.back()[ProgramName->size()] = '\0';
-    ArgV.push_back(ArgVStorage.back().get());
-  }
-
-  for (auto &Arg : Args) {
-    ArgVStorage.push_back(std::make_unique<char[]>(Arg.size() + 1));
-    llvm::copy(Arg, &ArgVStorage.back()[0]);
-    ArgVStorage.back()[Arg.size()] = '\0';
-    ArgV.push_back(ArgVStorage.back().get());
-  }
-  ArgV.push_back(nullptr);
-
-  return Main(Args.size() + !!ProgramName, ArgV.data());
-}
-
 CtorDtorIterator::CtorDtorIterator(const GlobalVariable *GV, bool End)
   : InitList(
       GV ? dyn_cast_or_null<ConstantArray>(GV->getInitializer()) : nullptr),
@@ -261,8 +235,8 @@ DynamicLibrarySearchGenerator::Load(const char *FileName, char GlobalPrefix,
 }
 
 Error DynamicLibrarySearchGenerator::tryToGenerate(
-    LookupKind K, JITDylib &JD, JITDylibLookupFlags JDLookupFlags,
-    const SymbolLookupSet &Symbols) {
+    LookupState &LS, LookupKind K, JITDylib &JD,
+    JITDylibLookupFlags JDLookupFlags, const SymbolLookupSet &Symbols) {
   orc::SymbolMap NewSymbols;
 
   bool HasGlobalPrefix = (GlobalPrefix != '\0');
@@ -322,7 +296,8 @@ StaticLibraryDefinitionGenerator::Load(ObjectLayer &L, const char *FileName,
       auto ObjTT = Obj.getTriple();
       if (ObjTT.getArch() == TT.getArch() &&
           ObjTT.getSubArch() == TT.getSubArch() &&
-          ObjTT.getVendor() == TT.getVendor()) {
+          (TT.getVendor() == Triple::UnknownVendor ||
+           ObjTT.getVendor() == TT.getVendor())) {
         // We found a match. Create an instance from a buffer covering this
         // slice.
         auto SliceBuffer = MemoryBuffer::getFileSlice(FileName, Obj.getSize(),
@@ -364,8 +339,8 @@ StaticLibraryDefinitionGenerator::Create(
 }
 
 Error StaticLibraryDefinitionGenerator::tryToGenerate(
-    LookupKind K, JITDylib &JD, JITDylibLookupFlags JDLookupFlags,
-    const SymbolLookupSet &Symbols) {
+    LookupState &LS, LookupKind K, JITDylib &JD,
+    JITDylibLookupFlags JDLookupFlags, const SymbolLookupSet &Symbols) {
 
   // Don't materialize symbols from static archives unless this is a static
   // lookup.
@@ -396,8 +371,7 @@ Error StaticLibraryDefinitionGenerator::tryToGenerate(
     MemoryBufferRef ChildBufferRef(ChildBufferInfo.first,
                                    ChildBufferInfo.second);
 
-    if (auto Err = L.add(JD, MemoryBuffer::getMemBuffer(ChildBufferRef, false),
-                         VModuleKey()))
+    if (auto Err = L.add(JD, MemoryBuffer::getMemBuffer(ChildBufferRef, false)))
       return Err;
   }
 
diff --git a/llvm/lib/ExecutionEngine/Orc/IRCompileLayer.cpp b/llvm/lib/ExecutionEngine/Orc/IRCompileLayer.cpp
index 023940dc8298..aadc437c80c4 100644
--- a/llvm/lib/ExecutionEngine/Orc/IRCompileLayer.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/IRCompileLayer.cpp
@@ -25,7 +25,7 @@ void IRCompileLayer::setNotifyCompiled(NotifyCompiledFunction NotifyCompiled) {
   this->NotifyCompiled = std::move(NotifyCompiled);
 }
 
-void IRCompileLayer::emit(MaterializationResponsibility R,
+void IRCompileLayer::emit(std::unique_ptr<MaterializationResponsibility> R,
                           ThreadSafeModule TSM) {
   assert(TSM && "Module must not be null");
 
@@ -33,13 +33,13 @@ void IRCompileLayer::emit(MaterializationResponsibility R,
     {
       std::lock_guard<std::mutex> Lock(IRLayerMutex);
       if (NotifyCompiled)
-        NotifyCompiled(R.getVModuleKey(), std::move(TSM));
+        NotifyCompiled(*R, std::move(TSM));
       else
         TSM = ThreadSafeModule();
     }
     BaseLayer.emit(std::move(R), std::move(*Obj));
   } else {
-    R.failMaterialization();
+    R->failMaterialization();
     getExecutionSession().reportError(Obj.takeError());
   }
 }
diff --git a/llvm/lib/ExecutionEngine/Orc/IRTransformLayer.cpp b/llvm/lib/ExecutionEngine/Orc/IRTransformLayer.cpp
index 511248f83b25..d5b11349277c 100644
--- a/llvm/lib/ExecutionEngine/Orc/IRTransformLayer.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/IRTransformLayer.cpp
@@ -17,14 +17,14 @@ IRTransformLayer::IRTransformLayer(ExecutionSession &ES, IRLayer &BaseLayer,
     : IRLayer(ES, BaseLayer.getManglingOptions()), BaseLayer(BaseLayer),
       Transform(std::move(Transform)) {}
 
-void IRTransformLayer::emit(MaterializationResponsibility R,
+void IRTransformLayer::emit(std::unique_ptr<MaterializationResponsibility> R,
                             ThreadSafeModule TSM) {
   assert(TSM && "Module must not be null");
 
-  if (auto TransformedTSM = Transform(std::move(TSM), R))
+  if (auto TransformedTSM = Transform(std::move(TSM), *R))
     BaseLayer.emit(std::move(R), std::move(*TransformedTSM));
   else {
-    R.failMaterialization();
+    R->failMaterialization();
     getExecutionSession().reportError(TransformedTSM.takeError());
   }
 }
diff --git a/llvm/lib/ExecutionEngine/Orc/IndirectionUtils.cpp b/llvm/lib/ExecutionEngine/Orc/IndirectionUtils.cpp
index 031b1afefc9d..1cfcf8ae943d 100644
--- a/llvm/lib/ExecutionEngine/Orc/IndirectionUtils.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/IndirectionUtils.cpp
@@ -25,20 +25,20 @@ public:
   using CompileFunction = JITCompileCallbackManager::CompileFunction;
 
   CompileCallbackMaterializationUnit(SymbolStringPtr Name,
-                                     CompileFunction Compile, VModuleKey K)
+                                     CompileFunction Compile)
       : MaterializationUnit(SymbolFlagsMap({{Name, JITSymbolFlags::Exported}}),
-                            nullptr, std::move(K)),
+                            nullptr),
         Name(std::move(Name)), Compile(std::move(Compile)) {}
 
   StringRef getName() const override { return "<Compile Callbacks>"; }
 
 private:
-  void materialize(MaterializationResponsibility R) override {
+  void materialize(std::unique_ptr<MaterializationResponsibility> R) override {
     SymbolMap Result;
     Result[Name] = JITEvaluatedSymbol(Compile(), JITSymbolFlags::Exported);
     // No dependencies, so these calls cannot fail.
-    cantFail(R.notifyResolved(Result));
-    cantFail(R.notifyEmitted());
+    cantFail(R->notifyResolved(Result));
+    cantFail(R->notifyEmitted());
   }
 
   void discard(const JITDylib &JD, const SymbolStringPtr &Name) override {
@@ -54,8 +54,8 @@ private:
 namespace llvm {
 namespace orc {
 
+TrampolinePool::~TrampolinePool() {}
 void IndirectStubsManager::anchor() {}
-void TrampolinePool::anchor() {}
 
 Expected<JITTargetAddress>
 JITCompileCallbackManager::getCompileCallback(CompileFunction Compile) {
@@ -65,10 +65,9 @@ JITCompileCallbackManager::getCompileCallback(CompileFunction Compile) {
 
     std::lock_guard<std::mutex> Lock(CCMgrMutex);
     AddrToSymbol[*TrampolineAddr] = CallbackName;
-    cantFail(CallbacksJD.define(
-        std::make_unique<CompileCallbackMaterializationUnit>(
-            std::move(CallbackName), std::move(Compile),
-            ES.allocateVModule())));
+    cantFail(
+        CallbacksJD.define(std::make_unique<CompileCallbackMaterializationUnit>(
+            std::move(CallbackName), std::move(Compile))));
     return *TrampolineAddr;
   } else
     return TrampolineAddr.takeError();
@@ -149,7 +148,7 @@ createLocalCompileCallbackManager(const Triple &T, ExecutionSession &ES,
     }
 
     case Triple::x86_64: {
-      if ( T.getOS() == Triple::OSType::Win32 ) {
+      if (T.getOS() == Triple::OSType::Win32) {
         typedef orc::LocalJITCompileCallbackManager<orc::OrcX86_64_Win32> CCMgrT;
         return CCMgrT::Create(ES, ErrorHandlerAddress);
       } else {
diff --git a/llvm/lib/ExecutionEngine/Orc/LLJIT.cpp b/llvm/lib/ExecutionEngine/Orc/LLJIT.cpp
index 713a48fbf3eb..c368c1e37134 100644
--- a/llvm/lib/ExecutionEngine/Orc/LLJIT.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/LLJIT.cpp
@@ -11,8 +11,10 @@
 #include "llvm/ExecutionEngine/JITLink/JITLinkMemoryManager.h"
 #include "llvm/ExecutionEngine/Orc/MachOPlatform.h"
 #include "llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h"
-#include "llvm/ExecutionEngine/Orc/OrcError.h"
+#include "llvm/ExecutionEngine/Orc/ObjectTransformLayer.h"
 #include "llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h"
+#include "llvm/ExecutionEngine/Orc/Shared/OrcError.h"
+#include "llvm/ExecutionEngine/Orc/TargetProcessControl.h"
 #include "llvm/ExecutionEngine/SectionMemoryManager.h"
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/IRBuilder.h"
@@ -87,8 +89,9 @@ class GenericLLVMIRPlatform : public Platform {
 public:
   GenericLLVMIRPlatform(GenericLLVMIRPlatformSupport &S) : S(S) {}
   Error setupJITDylib(JITDylib &JD) override;
-  Error notifyAdding(JITDylib &JD, const MaterializationUnit &MU) override;
-  Error notifyRemoving(JITDylib &JD, VModuleKey K) override {
+  Error notifyAdding(ResourceTracker &RT,
+                     const MaterializationUnit &MU) override;
+  Error notifyRemoving(ResourceTracker &RT) override {
     // Noop -- Nothing to do (yet).
     return Error::success();
   }
@@ -186,7 +189,8 @@ public:
     return J.addIRModule(JD, ThreadSafeModule(std::move(M), std::move(Ctx)));
   }
 
-  Error notifyAdding(JITDylib &JD, const MaterializationUnit &MU) {
+  Error notifyAdding(ResourceTracker &RT, const MaterializationUnit &MU) {
+    auto &JD = RT.getJITDylib();
     if (auto &InitSym = MU.getInitializerSymbol())
       InitSymbols[&JD].add(InitSym, SymbolLookupFlags::WeaklyReferencedSymbol);
     else {
@@ -235,7 +239,7 @@ public:
       });
       for (auto DeinitFnAddr : *Deinitializers) {
         LLVM_DEBUG({
-          dbgs() << "  Running init " << formatv("{0:x16}", DeinitFnAddr)
+          dbgs() << "  Running deinit " << formatv("{0:x16}", DeinitFnAddr)
                  << "...\n";
         });
         auto *DeinitFn = jitTargetAddressToFunction<void (*)()>(DeinitFnAddr);
@@ -260,23 +264,23 @@ private:
       return std::move(Err);
 
     DenseMap<JITDylib *, SymbolLookupSet> LookupSymbols;
-    std::vector<JITDylib *> DFSLinkOrder;
+    std::vector<JITDylibSP> DFSLinkOrder;
 
     getExecutionSession().runSessionLocked([&]() {
-        DFSLinkOrder = getDFSLinkOrder(JD);
+      DFSLinkOrder = JD.getDFSLinkOrder();
 
-        for (auto *NextJD : DFSLinkOrder) {
-          auto IFItr = InitFunctions.find(NextJD);
-          if (IFItr != InitFunctions.end()) {
-            LookupSymbols[NextJD] = std::move(IFItr->second);
-            InitFunctions.erase(IFItr);
-          }
+      for (auto &NextJD : DFSLinkOrder) {
+        auto IFItr = InitFunctions.find(NextJD.get());
+        if (IFItr != InitFunctions.end()) {
+          LookupSymbols[NextJD.get()] = std::move(IFItr->second);
+          InitFunctions.erase(IFItr);
         }
-      });
+      }
+    });
 
     LLVM_DEBUG({
       dbgs() << "JITDylib init order is [ ";
-      for (auto *JD : llvm::reverse(DFSLinkOrder))
+      for (auto &JD : llvm::reverse(DFSLinkOrder))
         dbgs() << "\"" << JD->getName() << "\" ";
       dbgs() << "]\n";
       dbgs() << "Looking up init functions:\n";
@@ -310,26 +314,26 @@ private:
     auto LLJITRunAtExits = J.mangleAndIntern("__lljit_run_atexits");
 
     DenseMap<JITDylib *, SymbolLookupSet> LookupSymbols;
-    std::vector<JITDylib *> DFSLinkOrder;
+    std::vector<JITDylibSP> DFSLinkOrder;
 
     ES.runSessionLocked([&]() {
-        DFSLinkOrder = getDFSLinkOrder(JD);
+      DFSLinkOrder = JD.getDFSLinkOrder();
 
-        for (auto *NextJD : DFSLinkOrder) {
-          auto &JDLookupSymbols = LookupSymbols[NextJD];
-          auto DIFItr = DeInitFunctions.find(NextJD);
-          if (DIFItr != DeInitFunctions.end()) {
-            LookupSymbols[NextJD] = std::move(DIFItr->second);
-            DeInitFunctions.erase(DIFItr);
-          }
-          JDLookupSymbols.add(LLJITRunAtExits,
+      for (auto &NextJD : DFSLinkOrder) {
+        auto &JDLookupSymbols = LookupSymbols[NextJD.get()];
+        auto DIFItr = DeInitFunctions.find(NextJD.get());
+        if (DIFItr != DeInitFunctions.end()) {
+          LookupSymbols[NextJD.get()] = std::move(DIFItr->second);
+          DeInitFunctions.erase(DIFItr);
+        }
+        JDLookupSymbols.add(LLJITRunAtExits,
                             SymbolLookupFlags::WeaklyReferencedSymbol);
       }
     });
 
     LLVM_DEBUG({
       dbgs() << "JITDylib deinit order is [ ";
-      for (auto *JD : DFSLinkOrder)
+      for (auto &JD : DFSLinkOrder)
         dbgs() << "\"" << JD->getName() << "\" ";
       dbgs() << "]\n";
       dbgs() << "Looking up deinit functions:\n";
@@ -343,8 +347,8 @@ private:
       return LookupResult.takeError();
 
     std::vector<JITTargetAddress> DeInitializers;
-    for (auto *NextJD : DFSLinkOrder) {
-      auto DeInitsItr = LookupResult->find(NextJD);
+    for (auto &NextJD : DFSLinkOrder) {
+      auto DeInitsItr = LookupResult->find(NextJD.get());
       assert(DeInitsItr != LookupResult->end() &&
              "Every JD should have at least __lljit_run_atexits");
 
@@ -360,46 +364,23 @@ private:
     return DeInitializers;
   }
 
-  // Returns a DFS traversal order of the JITDylibs reachable (via
-  // links-against edges) from JD, starting with JD itself.
-  static std::vector<JITDylib *> getDFSLinkOrder(JITDylib &JD) {
-    std::vector<JITDylib *> DFSLinkOrder;
-    std::vector<JITDylib *> WorkStack({&JD});
-    DenseSet<JITDylib *> Visited;
-
-    while (!WorkStack.empty()) {
-      auto &NextJD = *WorkStack.back();
-      WorkStack.pop_back();
-      if (Visited.count(&NextJD))
-        continue;
-      Visited.insert(&NextJD);
-      DFSLinkOrder.push_back(&NextJD);
-      NextJD.withLinkOrderDo([&](const JITDylibSearchOrder &LinkOrder) {
-        for (auto &KV : LinkOrder)
-          WorkStack.push_back(KV.first);
-      });
-    }
-
-    return DFSLinkOrder;
-  }
-
   /// Issue lookups for all init symbols required to initialize JD (and any
   /// JITDylibs that it depends on).
   Error issueInitLookups(JITDylib &JD) {
     DenseMap<JITDylib *, SymbolLookupSet> RequiredInitSymbols;
-    std::vector<JITDylib *> DFSLinkOrder;
+    std::vector<JITDylibSP> DFSLinkOrder;
 
     getExecutionSession().runSessionLocked([&]() {
-        DFSLinkOrder = getDFSLinkOrder(JD);
+      DFSLinkOrder = JD.getDFSLinkOrder();
 
-        for (auto *NextJD : DFSLinkOrder) {
-          auto ISItr = InitSymbols.find(NextJD);
-          if (ISItr != InitSymbols.end()) {
-            RequiredInitSymbols[NextJD] = std::move(ISItr->second);
-            InitSymbols.erase(ISItr);
-          }
+      for (auto &NextJD : DFSLinkOrder) {
+        auto ISItr = InitSymbols.find(NextJD.get());
+        if (ISItr != InitSymbols.end()) {
+          RequiredInitSymbols[NextJD.get()] = std::move(ISItr->second);
+          InitSymbols.erase(ISItr);
         }
-      });
+      }
+    });
 
     return Platform::lookupInitSymbols(getExecutionSession(),
                                        RequiredInitSymbols)
@@ -468,9 +449,9 @@ Error GenericLLVMIRPlatform::setupJITDylib(JITDylib &JD) {
   return S.setupJITDylib(JD);
 }
 
-Error GenericLLVMIRPlatform::notifyAdding(JITDylib &JD,
+Error GenericLLVMIRPlatform::notifyAdding(ResourceTracker &RT,
                                           const MaterializationUnit &MU) {
-  return S.notifyAdding(JD, MU);
+  return S.notifyAdding(RT, MU);
 }
 
 Expected<ThreadSafeModule>
@@ -927,7 +908,7 @@ LLJIT::PlatformSupport::~PlatformSupport() {}
 
 Error LLJITBuilderState::prepareForConstruction() {
 
-  LLVM_DEBUG(dbgs() << "Preparing to create LLIT instance...\n");
+  LLVM_DEBUG(dbgs() << "Preparing to create LLJIT instance...\n");
 
   if (!JTMB) {
     LLVM_DEBUG({
@@ -973,12 +954,18 @@ Error LLJITBuilderState::prepareForConstruction() {
       JTMB->setRelocationModel(Reloc::PIC_);
       JTMB->setCodeModel(CodeModel::Small);
       CreateObjectLinkingLayer =
-          [](ExecutionSession &ES,
-             const Triple &) -> std::unique_ptr<ObjectLayer> {
-        auto ObjLinkingLayer = std::make_unique<ObjectLinkingLayer>(
-            ES, std::make_unique<jitlink::InProcessMemoryManager>());
+          [TPC = this->TPC](
+              ExecutionSession &ES,
+              const Triple &) -> Expected<std::unique_ptr<ObjectLayer>> {
+        std::unique_ptr<ObjectLinkingLayer> ObjLinkingLayer;
+        if (TPC)
+          ObjLinkingLayer =
+              std::make_unique<ObjectLinkingLayer>(ES, TPC->getMemMgr());
+        else
+          ObjLinkingLayer = std::make_unique<ObjectLinkingLayer>(
+              ES, std::make_unique<jitlink::InProcessMemoryManager>());
         ObjLinkingLayer->addPlugin(std::make_unique<EHFrameRegistrationPlugin>(
-            jitlink::InProcessEHFrameRegistrar::getInstance()));
+            ES, std::make_unique<jitlink::InProcessEHFrameRegistrar>()));
         return std::move(ObjLinkingLayer);
       };
     }
@@ -990,23 +977,33 @@ Error LLJITBuilderState::prepareForConstruction() {
 LLJIT::~LLJIT() {
   if (CompileThreads)
     CompileThreads->wait();
+  if (auto Err = ES->endSession())
+    ES->reportError(std::move(Err));
 }
 
-Error LLJIT::addIRModule(JITDylib &JD, ThreadSafeModule TSM) {
+Error LLJIT::addIRModule(ResourceTrackerSP RT, ThreadSafeModule TSM) {
   assert(TSM && "Can not add null module");
 
   if (auto Err =
           TSM.withModuleDo([&](Module &M) { return applyDataLayout(M); }))
     return Err;
 
-  return InitHelperTransformLayer->add(JD, std::move(TSM),
-                                       ES->allocateVModule());
+  return InitHelperTransformLayer->add(std::move(RT), std::move(TSM));
 }
 
-Error LLJIT::addObjectFile(JITDylib &JD, std::unique_ptr<MemoryBuffer> Obj) {
+Error LLJIT::addIRModule(JITDylib &JD, ThreadSafeModule TSM) {
+  return addIRModule(JD.getDefaultResourceTracker(), std::move(TSM));
+}
+
+Error LLJIT::addObjectFile(ResourceTrackerSP RT,
+                           std::unique_ptr<MemoryBuffer> Obj) {
   assert(Obj && "Can not add null object");
 
-  return ObjTransformLayer.add(JD, std::move(Obj), ES->allocateVModule());
+  return ObjTransformLayer->add(std::move(RT), std::move(Obj));
+}
+
+Error LLJIT::addObjectFile(JITDylib &JD, std::unique_ptr<MemoryBuffer> Obj) {
+  return addObjectFile(JD.getDefaultResourceTracker(), std::move(Obj));
 }
 
 Expected<JITEvaluatedSymbol> LLJIT::lookupLinkerMangled(JITDylib &JD,
@@ -1015,7 +1012,7 @@ Expected<JITEvaluatedSymbol> LLJIT::lookupLinkerMangled(JITDylib &JD,
       makeJITDylibSearchOrder(&JD, JITDylibLookupFlags::MatchAllSymbols), Name);
 }
 
-std::unique_ptr<ObjectLayer>
+Expected<std::unique_ptr<ObjectLayer>>
 LLJIT::createObjectLinkingLayer(LLJITBuilderState &S, ExecutionSession &ES) {
 
   // If the config state provided an ObjectLinkingLayer factory then use it.
@@ -1061,9 +1058,7 @@ LLJIT::createCompileFunction(LLJITBuilderState &S,
 
 LLJIT::LLJIT(LLJITBuilderState &S, Error &Err)
     : ES(S.ES ? std::move(S.ES) : std::make_unique<ExecutionSession>()), Main(),
-      DL(""), TT(S.JTMB->getTargetTriple()),
-      ObjLinkingLayer(createObjectLinkingLayer(S, *ES)),
-      ObjTransformLayer(*this->ES, *ObjLinkingLayer) {
+      DL(""), TT(S.JTMB->getTargetTriple()) {
 
   ErrorAsOutParameter _(&Err);
 
@@ -1083,6 +1078,15 @@ LLJIT::LLJIT(LLJITBuilderState &S, Error &Err)
     return;
   }
 
+  auto ObjLayer = createObjectLinkingLayer(S, *ES);
+  if (!ObjLayer) {
+    Err = ObjLayer.takeError();
+    return;
+  }
+  ObjLinkingLayer = std::move(*ObjLayer);
+  ObjTransformLayer =
+      std::make_unique<ObjectTransformLayer>(*ES, *ObjLinkingLayer);
+
   {
     auto CompileFunction = createCompileFunction(S, std::move(*S.JTMB));
     if (!CompileFunction) {
@@ -1090,7 +1094,7 @@ LLJIT::LLJIT(LLJITBuilderState &S, Error &Err)
       return;
     }
     CompileLayer = std::make_unique<IRCompileLayer>(
-        *ES, ObjTransformLayer, std::move(*CompileFunction));
+        *ES, *ObjTransformLayer, std::move(*CompileFunction));
     TransformLayer = std::make_unique<IRTransformLayer>(*ES, *CompileLayer);
     InitHelperTransformLayer =
         std::make_unique<IRTransformLayer>(*ES, *TransformLayer);
@@ -1102,15 +1106,17 @@ LLJIT::LLJIT(LLJITBuilderState &S, Error &Err)
         std::make_unique<ThreadPool>(hardware_concurrency(S.NumCompileThreads));
     ES->setDispatchMaterialization(
         [this](std::unique_ptr<MaterializationUnit> MU,
-               MaterializationResponsibility MR) {
-          // FIXME: Switch to move capture once ThreadPool uses unique_function.
-          auto SharedMU = std::shared_ptr<MaterializationUnit>(std::move(MU));
-          auto SharedMR =
-              std::make_shared<MaterializationResponsibility>(std::move(MR));
-          auto Work = [SharedMU, SharedMR]() mutable {
-            SharedMU->materialize(std::move(*SharedMR));
-          };
-          CompileThreads->async(std::move(Work));
+               std::unique_ptr<MaterializationResponsibility> MR) {
+          // FIXME: We should be able to use move-capture here, but ThreadPool's
+          // AsyncTaskTys are std::functions rather than unique_functions
+          // (because MSVC's std::packaged_tasks don't support move-only types).
+          // Fix this when all the above gets sorted out.
+          CompileThreads->async(
+              [UnownedMU = MU.release(), UnownedMR = MR.release()]() mutable {
+                std::unique_ptr<MaterializationUnit> MU(UnownedMU);
+                std::unique_ptr<MaterializationResponsibility> MR(UnownedMR);
+                MU->materialize(std::move(MR));
+              });
         });
   }
 
@@ -1172,7 +1178,7 @@ Error LLLazyJIT::addLazyIRModule(JITDylib &JD, ThreadSafeModule TSM) {
           [&](Module &M) -> Error { return applyDataLayout(M); }))
     return Err;
 
-  return CODLayer->add(JD, std::move(TSM), ES->allocateVModule());
+  return CODLayer->add(JD, std::move(TSM));
 }
 
 LLLazyJIT::LLLazyJIT(LLLazyJITBuilderState &S, Error &Err) : LLJIT(S, Err) {
diff --git a/llvm/lib/ExecutionEngine/Orc/Layer.cpp b/llvm/lib/ExecutionEngine/Orc/Layer.cpp
index 61e7ab5ae68b..5e27e343d23b 100644
--- a/llvm/lib/ExecutionEngine/Orc/Layer.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/Layer.cpp
@@ -22,16 +22,18 @@ namespace orc {
 
 IRLayer::~IRLayer() {}
 
-Error IRLayer::add(JITDylib &JD, ThreadSafeModule TSM, VModuleKey K) {
+Error IRLayer::add(ResourceTrackerSP RT, ThreadSafeModule TSM) {
+  assert(RT && "RT can not be null");
+  auto &JD = RT->getJITDylib();
   return JD.define(std::make_unique<BasicIRLayerMaterializationUnit>(
-      *this, *getManglingOptions(), std::move(TSM), std::move(K)));
+                       *this, *getManglingOptions(), std::move(TSM)),
+                   std::move(RT));
 }
 
 IRMaterializationUnit::IRMaterializationUnit(
     ExecutionSession &ES, const IRSymbolMapper::ManglingOptions &MO,
-    ThreadSafeModule TSM, VModuleKey K)
-    : MaterializationUnit(SymbolFlagsMap(), nullptr, std::move(K)),
-      TSM(std::move(TSM)) {
+    ThreadSafeModule TSM)
+    : MaterializationUnit(SymbolFlagsMap(), nullptr), TSM(std::move(TSM)) {
 
   assert(this->TSM && "Module must not be null");
 
@@ -83,26 +85,22 @@ IRMaterializationUnit::IRMaterializationUnit(
     if (!llvm::empty(getStaticInitGVs(M))) {
       size_t Counter = 0;
 
-      while (true) {
+      do {
         std::string InitSymbolName;
         raw_string_ostream(InitSymbolName)
             << "$." << M.getModuleIdentifier() << ".__inits." << Counter++;
         InitSymbol = ES.intern(InitSymbolName);
-        if (SymbolFlags.count(InitSymbol))
-          continue;
-        SymbolFlags[InitSymbol] =
-            JITSymbolFlags::MaterializationSideEffectsOnly;
-        break;
-      }
+      } while (SymbolFlags.count(InitSymbol));
+
+      SymbolFlags[InitSymbol] = JITSymbolFlags::MaterializationSideEffectsOnly;
     }
   });
 }
 
 IRMaterializationUnit::IRMaterializationUnit(
-    ThreadSafeModule TSM, VModuleKey K, SymbolFlagsMap SymbolFlags,
+    ThreadSafeModule TSM, SymbolFlagsMap SymbolFlags,
     SymbolStringPtr InitSymbol, SymbolNameToDefinitionMap SymbolToDefinition)
-    : MaterializationUnit(std::move(SymbolFlags), std::move(InitSymbol),
-                          std::move(K)),
+    : MaterializationUnit(std::move(SymbolFlags), std::move(InitSymbol)),
       TSM(std::move(TSM)), SymbolToDefinition(std::move(SymbolToDefinition)) {}
 
 StringRef IRMaterializationUnit::getName() const {
@@ -129,14 +127,12 @@ void IRMaterializationUnit::discard(const JITDylib &JD,
 }
 
 BasicIRLayerMaterializationUnit::BasicIRLayerMaterializationUnit(
-    IRLayer &L, const IRSymbolMapper::ManglingOptions &MO, ThreadSafeModule TSM,
-    VModuleKey K)
-    : IRMaterializationUnit(L.getExecutionSession(), MO, std::move(TSM),
-                            std::move(K)),
-      L(L), K(std::move(K)) {}
+    IRLayer &L, const IRSymbolMapper::ManglingOptions &MO, ThreadSafeModule TSM)
+    : IRMaterializationUnit(L.getExecutionSession(), MO, std::move(TSM)), L(L) {
+}
 
 void BasicIRLayerMaterializationUnit::materialize(
-    MaterializationResponsibility R) {
+    std::unique_ptr<MaterializationResponsibility> R) {
 
   // Throw away the SymbolToDefinition map: it's not usable after we hand
   // off the module.
@@ -147,8 +143,8 @@ void BasicIRLayerMaterializationUnit::materialize(
     TSM = cloneToNewContext(TSM);
 
 #ifndef NDEBUG
-  auto &ES = R.getTargetJITDylib().getExecutionSession();
-  auto &N = R.getTargetJITDylib().getName();
+  auto &ES = R->getTargetJITDylib().getExecutionSession();
+  auto &N = R->getTargetJITDylib().getName();
 #endif // NDEBUG
 
   LLVM_DEBUG(ES.runSessionLocked(
@@ -163,17 +159,17 @@ ObjectLayer::ObjectLayer(ExecutionSession &ES) : ES(ES) {}
 
 ObjectLayer::~ObjectLayer() {}
 
-Error ObjectLayer::add(JITDylib &JD, std::unique_ptr<MemoryBuffer> O,
-                       VModuleKey K) {
-  auto ObjMU = BasicObjectLayerMaterializationUnit::Create(*this, std::move(K),
-                                                           std::move(O));
+Error ObjectLayer::add(ResourceTrackerSP RT, std::unique_ptr<MemoryBuffer> O) {
+  assert(RT && "RT can not be null");
+  auto ObjMU = BasicObjectLayerMaterializationUnit::Create(*this, std::move(O));
   if (!ObjMU)
     return ObjMU.takeError();
-  return JD.define(std::move(*ObjMU));
+  auto &JD = RT->getJITDylib();
+  return JD.define(std::move(*ObjMU), std::move(RT));
 }
 
 Expected<std::unique_ptr<BasicObjectLayerMaterializationUnit>>
-BasicObjectLayerMaterializationUnit::Create(ObjectLayer &L, VModuleKey K,
+BasicObjectLayerMaterializationUnit::Create(ObjectLayer &L,
                                             std::unique_ptr<MemoryBuffer> O) {
   auto ObjSymInfo =
       getObjectSymbolInfo(L.getExecutionSession(), O->getMemBufferRef());
@@ -186,15 +182,14 @@ BasicObjectLayerMaterializationUnit::Create(ObjectLayer &L, VModuleKey K,
 
   return std::unique_ptr<BasicObjectLayerMaterializationUnit>(
       new BasicObjectLayerMaterializationUnit(
-          L, K, std::move(O), std::move(SymbolFlags), std::move(InitSymbol)));
+          L, std::move(O), std::move(SymbolFlags), std::move(InitSymbol)));
 }
 
 BasicObjectLayerMaterializationUnit::BasicObjectLayerMaterializationUnit(
-    ObjectLayer &L, VModuleKey K, std::unique_ptr<MemoryBuffer> O,
-    SymbolFlagsMap SymbolFlags, SymbolStringPtr InitSymbol)
-    : MaterializationUnit(std::move(SymbolFlags), std::move(InitSymbol),
-                          std::move(K)),
-      L(L), O(std::move(O)) {}
+    ObjectLayer &L, std::unique_ptr<MemoryBuffer> O, SymbolFlagsMap SymbolFlags,
+    SymbolStringPtr InitSymbol)
+    : MaterializationUnit(std::move(SymbolFlags), std::move(InitSymbol)), L(L),
+      O(std::move(O)) {}
 
 StringRef BasicObjectLayerMaterializationUnit::getName() const {
   if (O)
@@ -203,7 +198,7 @@ StringRef BasicObjectLayerMaterializationUnit::getName() const {
 }
 
 void BasicObjectLayerMaterializationUnit::materialize(
-    MaterializationResponsibility R) {
+    std::unique_ptr<MaterializationResponsibility> R) {
   L.emit(std::move(R), std::move(O));
 }
 
diff --git a/llvm/lib/ExecutionEngine/Orc/LazyReexports.cpp b/llvm/lib/ExecutionEngine/Orc/LazyReexports.cpp
index 153f6b80784f..e1f494415e86 100644
--- a/llvm/lib/ExecutionEngine/Orc/LazyReexports.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/LazyReexports.cpp
@@ -75,27 +75,31 @@ void LazyCallThroughManager::resolveTrampolineLandingAddress(
   if (!Entry)
     return NotifyLandingResolved(reportCallThroughError(Entry.takeError()));
 
-  ES.lookup(
-      LookupKind::Static,
-      makeJITDylibSearchOrder(Entry->SourceJD,
-                              JITDylibLookupFlags::MatchAllSymbols),
-      SymbolLookupSet({Entry->SymbolName}), SymbolState::Ready,
-      [this, TrampolineAddr, SymbolName = Entry->SymbolName,
-       NotifyLandingResolved = std::move(NotifyLandingResolved)](
-          Expected<SymbolMap> Result) mutable {
-        if (Result) {
-          assert(Result->size() == 1 && "Unexpected result size");
-          assert(Result->count(SymbolName) && "Unexpected result value");
-          JITTargetAddress LandingAddr = (*Result)[SymbolName].getAddress();
+  // Declaring SLS and the callback outside of the call to ES.lookup is a
+  // workaround to fix build failures on AIX and on z/OS platforms.
+  SymbolLookupSet SLS({Entry->SymbolName});
+  auto Callback = [this, TrampolineAddr, SymbolName = Entry->SymbolName,
+                   NotifyLandingResolved = std::move(NotifyLandingResolved)](
+                      Expected<SymbolMap> Result) mutable {
+    if (Result) {
+      assert(Result->size() == 1 && "Unexpected result size");
+      assert(Result->count(SymbolName) && "Unexpected result value");
+      JITTargetAddress LandingAddr = (*Result)[SymbolName].getAddress();
 
-          if (auto Err = notifyResolved(TrampolineAddr, LandingAddr))
-            NotifyLandingResolved(reportCallThroughError(std::move(Err)));
-          else
-            NotifyLandingResolved(LandingAddr);
-        } else
-          NotifyLandingResolved(reportCallThroughError(Result.takeError()));
-      },
-      NoDependenciesToRegister);
+      if (auto Err = notifyResolved(TrampolineAddr, LandingAddr))
+        NotifyLandingResolved(reportCallThroughError(std::move(Err)));
+      else
+        NotifyLandingResolved(LandingAddr);
+    } else {
+      NotifyLandingResolved(reportCallThroughError(Result.takeError()));
+    }
+  };
+
+  ES.lookup(LookupKind::Static,
+            makeJITDylibSearchOrder(Entry->SourceJD,
+                                    JITDylibLookupFlags::MatchAllSymbols),
+            std::move(SLS), SymbolState::Ready, std::move(Callback),
+            NoDependenciesToRegister);
 }
 
 Expected<std::unique_ptr<LazyCallThroughManager>>
@@ -139,9 +143,8 @@ createLocalLazyCallThroughManager(const Triple &T, ExecutionSession &ES,
 
 LazyReexportsMaterializationUnit::LazyReexportsMaterializationUnit(
     LazyCallThroughManager &LCTManager, IndirectStubsManager &ISManager,
-    JITDylib &SourceJD, SymbolAliasMap CallableAliases, ImplSymbolMap *SrcJDLoc,
-    VModuleKey K)
-    : MaterializationUnit(extractFlags(CallableAliases), nullptr, std::move(K)),
+    JITDylib &SourceJD, SymbolAliasMap CallableAliases, ImplSymbolMap *SrcJDLoc)
+    : MaterializationUnit(extractFlags(CallableAliases), nullptr),
       LCTManager(LCTManager), ISManager(ISManager), SourceJD(SourceJD),
       CallableAliases(std::move(CallableAliases)), AliaseeTable(SrcJDLoc) {}
 
@@ -150,8 +153,8 @@ StringRef LazyReexportsMaterializationUnit::getName() const {
 }
 
 void LazyReexportsMaterializationUnit::materialize(
-    MaterializationResponsibility R) {
-  auto RequestedSymbols = R.getRequestedSymbols();
+    std::unique_ptr<MaterializationResponsibility> R) {
+  auto RequestedSymbols = R->getRequestedSymbols();
 
   SymbolAliasMap RequestedAliases;
   for (auto &RequestedSymbol : RequestedSymbols) {
@@ -162,8 +165,13 @@ void LazyReexportsMaterializationUnit::materialize(
   }
 
   if (!CallableAliases.empty())
-    R.replace(lazyReexports(LCTManager, ISManager, SourceJD,
-                            std::move(CallableAliases), AliaseeTable));
+    if (auto Err = R->replace(lazyReexports(LCTManager, ISManager, SourceJD,
+                                            std::move(CallableAliases),
+                                            AliaseeTable))) {
+      R->getExecutionSession().reportError(std::move(Err));
+      R->failMaterialization();
+      return;
+    }
 
   IndirectStubsManager::StubInitsMap StubInits;
   for (auto &Alias : RequestedAliases) {
@@ -178,7 +186,7 @@ void LazyReexportsMaterializationUnit::materialize(
     if (!CallThroughTrampoline) {
       SourceJD.getExecutionSession().reportError(
           CallThroughTrampoline.takeError());
-      R.failMaterialization();
+      R->failMaterialization();
       return;
     }
 
@@ -191,7 +199,7 @@ void LazyReexportsMaterializationUnit::materialize(
 
   if (auto Err = ISManager.createStubs(StubInits)) {
     SourceJD.getExecutionSession().reportError(std::move(Err));
-    R.failMaterialization();
+    R->failMaterialization();
     return;
   }
 
@@ -200,8 +208,8 @@ void LazyReexportsMaterializationUnit::materialize(
     Stubs[Alias.first] = ISManager.findStub(*Alias.first, false);
 
   // No registered dependencies, so these calls cannot fail.
-  cantFail(R.notifyResolved(Stubs));
-  cantFail(R.notifyEmitted());
+  cantFail(R->notifyResolved(Stubs));
+  cantFail(R->notifyEmitted());
 }
 
 void LazyReexportsMaterializationUnit::discard(const JITDylib &JD,
diff --git a/llvm/lib/ExecutionEngine/Orc/Legacy.cpp b/llvm/lib/ExecutionEngine/Orc/Legacy.cpp
deleted file mode 100644
index 67b804c37287..000000000000
--- a/llvm/lib/ExecutionEngine/Orc/Legacy.cpp
+++ /dev/null
@@ -1,68 +0,0 @@
-//===------- Legacy.cpp - Adapters for ExecutionEngine API interop --------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/ExecutionEngine/Orc/Legacy.h"
-
-namespace llvm {
-namespace orc {
-
-void SymbolResolver::anchor() {}
-
-JITSymbolResolverAdapter::JITSymbolResolverAdapter(
-    ExecutionSession &ES, SymbolResolver &R, MaterializationResponsibility *MR)
-    : ES(ES), R(R), MR(MR) {}
-
-void JITSymbolResolverAdapter::lookup(const LookupSet &Symbols,
-                                      OnResolvedFunction OnResolved) {
-  SymbolNameSet InternedSymbols;
-  for (auto &S : Symbols)
-    InternedSymbols.insert(ES.intern(S));
-
-  auto OnResolvedWithUnwrap = [OnResolved = std::move(OnResolved)](
-                                  Expected<SymbolMap> InternedResult) mutable {
-    if (!InternedResult) {
-      OnResolved(InternedResult.takeError());
-      return;
-    }
-
-    LookupResult Result;
-    for (auto &KV : *InternedResult)
-      Result[*KV.first] = std::move(KV.second);
-    OnResolved(Result);
-  };
-
-  auto Q = std::make_shared<AsynchronousSymbolQuery>(
-      SymbolLookupSet(InternedSymbols), SymbolState::Resolved,
-      std::move(OnResolvedWithUnwrap));
-
-  auto Unresolved = R.lookup(Q, InternedSymbols);
-  if (Unresolved.empty()) {
-    if (MR)
-      MR->addDependenciesForAll(Q->QueryRegistrations);
-  } else
-    ES.legacyFailQuery(*Q, make_error<SymbolsNotFound>(std::move(Unresolved)));
-}
-
-Expected<JITSymbolResolverAdapter::LookupSet>
-JITSymbolResolverAdapter::getResponsibilitySet(const LookupSet &Symbols) {
-  SymbolNameSet InternedSymbols;
-  for (auto &S : Symbols)
-    InternedSymbols.insert(ES.intern(S));
-
-  auto InternedResult = R.getResponsibilitySet(InternedSymbols);
-  LookupSet Result;
-  for (auto &S : InternedResult) {
-    ResolvedStrings.insert(S);
-    Result.insert(*S);
-  }
-
-  return Result;
-}
-
-} // End namespace orc.
-} // End namespace llvm.
diff --git a/llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp b/llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp
index 15c3aa79a2a8..17b9465a0541 100644
--- a/llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp
@@ -159,7 +159,9 @@ Error MachOPlatform::setupJITDylib(JITDylib &JD) {
   return ObjLinkingLayer.add(JD, std::move(ObjBuffer));
 }
 
-Error MachOPlatform::notifyAdding(JITDylib &JD, const MaterializationUnit &MU) {
+Error MachOPlatform::notifyAdding(ResourceTracker &RT,
+                                  const MaterializationUnit &MU) {
+  auto &JD = RT.getJITDylib();
   const auto &InitSym = MU.getInitializerSymbol();
   if (!InitSym)
     return Error::success();
@@ -173,7 +175,7 @@ Error MachOPlatform::notifyAdding(JITDylib &JD, const MaterializationUnit &MU) {
   return Error::success();
 }
 
-Error MachOPlatform::notifyRemoving(JITDylib &JD, VModuleKey K) {
+Error MachOPlatform::notifyRemoving(ResourceTracker &RT) {
   llvm_unreachable("Not supported yet");
 }
 
@@ -185,19 +187,19 @@ MachOPlatform::getInitializerSequence(JITDylib &JD) {
            << JD.getName() << "\n";
   });
 
-  std::vector<JITDylib *> DFSLinkOrder;
+  std::vector<JITDylibSP> DFSLinkOrder;
 
   while (true) {
 
     DenseMap<JITDylib *, SymbolLookupSet> NewInitSymbols;
 
     ES.runSessionLocked([&]() {
-      DFSLinkOrder = getDFSLinkOrder(JD);
+      DFSLinkOrder = JD.getDFSLinkOrder();
 
-      for (auto *InitJD : DFSLinkOrder) {
-        auto RISItr = RegisteredInitSymbols.find(InitJD);
+      for (auto &InitJD : DFSLinkOrder) {
+        auto RISItr = RegisteredInitSymbols.find(InitJD.get());
         if (RISItr != RegisteredInitSymbols.end()) {
-          NewInitSymbols[InitJD] = std::move(RISItr->second);
+          NewInitSymbols[InitJD.get()] = std::move(RISItr->second);
           RegisteredInitSymbols.erase(RISItr);
         }
       }
@@ -229,14 +231,14 @@ MachOPlatform::getInitializerSequence(JITDylib &JD) {
   InitializerSequence FullInitSeq;
   {
     std::lock_guard<std::mutex> Lock(InitSeqsMutex);
-    for (auto *InitJD : reverse(DFSLinkOrder)) {
+    for (auto &InitJD : reverse(DFSLinkOrder)) {
       LLVM_DEBUG({
         dbgs() << "MachOPlatform: Appending inits for \"" << InitJD->getName()
                << "\" to sequence\n";
       });
-      auto ISItr = InitSeqs.find(InitJD);
+      auto ISItr = InitSeqs.find(InitJD.get());
       if (ISItr != InitSeqs.end()) {
-        FullInitSeq.emplace_back(InitJD, std::move(ISItr->second));
+        FullInitSeq.emplace_back(InitJD.get(), std::move(ISItr->second));
         InitSeqs.erase(ISItr);
       }
     }
@@ -247,39 +249,19 @@ MachOPlatform::getInitializerSequence(JITDylib &JD) {
 
 Expected<MachOPlatform::DeinitializerSequence>
 MachOPlatform::getDeinitializerSequence(JITDylib &JD) {
-  std::vector<JITDylib *> DFSLinkOrder = getDFSLinkOrder(JD);
+  std::vector<JITDylibSP> DFSLinkOrder = JD.getDFSLinkOrder();
 
   DeinitializerSequence FullDeinitSeq;
   {
     std::lock_guard<std::mutex> Lock(InitSeqsMutex);
-    for (auto *DeinitJD : DFSLinkOrder) {
-      FullDeinitSeq.emplace_back(DeinitJD, MachOJITDylibDeinitializers());
+    for (auto &DeinitJD : DFSLinkOrder) {
+      FullDeinitSeq.emplace_back(DeinitJD.get(), MachOJITDylibDeinitializers());
     }
   }
 
   return FullDeinitSeq;
 }
 
-std::vector<JITDylib *> MachOPlatform::getDFSLinkOrder(JITDylib &JD) {
-  std::vector<JITDylib *> Result, WorkStack({&JD});
-  DenseSet<JITDylib *> Visited;
-
-  while (!WorkStack.empty()) {
-    auto *NextJD = WorkStack.back();
-    WorkStack.pop_back();
-    if (Visited.count(NextJD))
-      continue;
-    Visited.insert(NextJD);
-    Result.push_back(NextJD);
-    NextJD->withLinkOrderDo([&](const JITDylibSearchOrder &LO) {
-      for (auto &KV : LO)
-        WorkStack.push_back(KV.first);
-    });
-  }
-
-  return Result;
-}
-
 void MachOPlatform::registerInitInfo(
     JITDylib &JD, JITTargetAddress ObjCImageInfoAddr,
     MachOJITDylibInitializers::SectionExtent ModInits,
@@ -319,13 +301,16 @@ void MachOPlatform::InitScraperPlugin::modifyPassConfig(
     MaterializationResponsibility &MR, const Triple &TT,
     jitlink::PassConfiguration &Config) {
 
+  if (!MR.getInitializerSymbol())
+    return;
+
   Config.PrePrunePasses.push_back([this, &MR](jitlink::LinkGraph &G) -> Error {
     JITLinkSymbolVector InitSectionSymbols;
     preserveInitSectionIfPresent(InitSectionSymbols, G, "__mod_init_func");
     preserveInitSectionIfPresent(InitSectionSymbols, G, "__objc_selrefs");
     preserveInitSectionIfPresent(InitSectionSymbols, G, "__objc_classlist");
 
-    if (!InitSymbolDeps.empty()) {
+    if (!InitSectionSymbols.empty()) {
       std::lock_guard<std::mutex> Lock(InitScraperMutex);
       InitSymbolDeps[&MR] = std::move(InitSectionSymbols);
     }
@@ -343,10 +328,8 @@ void MachOPlatform::InitScraperPlugin::modifyPassConfig(
 
     JITTargetAddress ObjCImageInfoAddr = 0;
     if (auto *ObjCImageInfoSec = G.findSectionByName("__objc_image_info")) {
-      if (auto Addr = jitlink::SectionRange(*ObjCImageInfoSec).getStart()) {
+      if (auto Addr = jitlink::SectionRange(*ObjCImageInfoSec).getStart())
         ObjCImageInfoAddr = Addr;
-        dbgs() << "Recorded __objc_imageinfo @ " << formatv("{0:x16}", Addr);
-      }
     }
 
     // Record __mod_init_func.
diff --git a/llvm/lib/ExecutionEngine/Orc/NullResolver.cpp b/llvm/lib/ExecutionEngine/Orc/NullResolver.cpp
deleted file mode 100644
index 5b4345b870bb..000000000000
--- a/llvm/lib/ExecutionEngine/Orc/NullResolver.cpp
+++ /dev/null
@@ -1,37 +0,0 @@
-//===---------- NullResolver.cpp - Reject symbol lookup requests ----------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/ExecutionEngine/Orc/NullResolver.h"
-
-#include "llvm/Support/ErrorHandling.h"
-
-namespace llvm {
-namespace orc {
-
-SymbolNameSet NullResolver::getResponsibilitySet(const SymbolNameSet &Symbols) {
-  return Symbols;
-}
-
-SymbolNameSet
-NullResolver::lookup(std::shared_ptr<AsynchronousSymbolQuery> Query,
-                     SymbolNameSet Symbols) {
-  assert(Symbols.empty() && "Null resolver: Symbols must be empty");
-  return Symbols;
-}
-
-JITSymbol NullLegacyResolver::findSymbol(const std::string &Name) {
-  llvm_unreachable("Unexpected cross-object symbol reference");
-}
-
-JITSymbol
-NullLegacyResolver::findSymbolInLogicalDylib(const std::string &Name) {
-  llvm_unreachable("Unexpected cross-object symbol reference");
-}
-
-} // End namespace orc.
-} // End namespace llvm.
diff --git a/llvm/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp b/llvm/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp
index 02066b458dfc..26f77acd91fc 100644
--- a/llvm/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp
@@ -24,34 +24,34 @@ namespace orc {
 
 class ObjectLinkingLayerJITLinkContext final : public JITLinkContext {
 public:
-  ObjectLinkingLayerJITLinkContext(ObjectLinkingLayer &Layer,
-                                   MaterializationResponsibility MR,
-                                   std::unique_ptr<MemoryBuffer> ObjBuffer)
-      : Layer(Layer), MR(std::move(MR)), ObjBuffer(std::move(ObjBuffer)) {}
+  ObjectLinkingLayerJITLinkContext(
+      ObjectLinkingLayer &Layer,
+      std::unique_ptr<MaterializationResponsibility> MR,
+      std::unique_ptr<MemoryBuffer> ObjBuffer)
+      : JITLinkContext(&MR->getTargetJITDylib()), Layer(Layer),
+        MR(std::move(MR)), ObjBuffer(std::move(ObjBuffer)) {}
 
   ~ObjectLinkingLayerJITLinkContext() {
     // If there is an object buffer return function then use it to
     // return ownership of the buffer.
-    if (Layer.ReturnObjectBuffer)
+    if (Layer.ReturnObjectBuffer && ObjBuffer)
       Layer.ReturnObjectBuffer(std::move(ObjBuffer));
   }
 
-  JITLinkMemoryManager &getMemoryManager() override { return *Layer.MemMgr; }
-
-  MemoryBufferRef getObjectBuffer() const override {
-    return ObjBuffer->getMemBufferRef();
-  }
+  JITLinkMemoryManager &getMemoryManager() override { return Layer.MemMgr; }
 
   void notifyFailed(Error Err) override {
+    for (auto &P : Layer.Plugins)
+      Err = joinErrors(std::move(Err), P->notifyFailed(*MR));
     Layer.getExecutionSession().reportError(std::move(Err));
-    MR.failMaterialization();
+    MR->failMaterialization();
   }
 
   void lookup(const LookupMap &Symbols,
               std::unique_ptr<JITLinkAsyncLookupContinuation> LC) override {
 
     JITDylibSearchOrder LinkOrder;
-    MR.getTargetJITDylib().withLinkOrderDo(
+    MR->getTargetJITDylib().withLinkOrderDo(
         [&](const JITDylibSearchOrder &LO) { LinkOrder = LO; });
 
     auto &ES = Layer.getExecutionSession();
@@ -71,9 +71,8 @@ public:
     }
 
     // OnResolve -- De-intern the symbols and pass the result to the linker.
-    auto OnResolve = [this, LookupContinuation = std::move(LC)](
-                         Expected<SymbolMap> Result) mutable {
-      auto Main = Layer.getExecutionSession().intern("_main");
+    auto OnResolve = [LookupContinuation =
+                          std::move(LC)](Expected<SymbolMap> Result) mutable {
       if (!Result)
         LookupContinuation->run(Result.takeError());
       else {
@@ -86,8 +85,8 @@ public:
 
     for (auto &KV : InternalNamedSymbolDeps) {
       SymbolDependenceMap InternalDeps;
-      InternalDeps[&MR.getTargetJITDylib()] = std::move(KV.second);
-      MR.addDependencies(KV.first, InternalDeps);
+      InternalDeps[&MR->getTargetJITDylib()] = std::move(KV.second);
+      MR->addDependencies(KV.first, InternalDeps);
     }
 
     ES.lookup(LookupKind::Static, LinkOrder, std::move(LookupSet),
@@ -97,7 +96,7 @@ public:
               });
   }
 
-  void notifyResolved(LinkGraph &G) override {
+  Error notifyResolved(LinkGraph &G) override {
     auto &ES = Layer.getExecutionSession();
 
     SymbolFlagsMap ExtraSymbolsToClaim;
@@ -116,7 +115,7 @@ public:
 
         InternedResult[InternedName] =
             JITEvaluatedSymbol(Sym->getAddress(), Flags);
-        if (AutoClaim && !MR.getSymbols().count(InternedName)) {
+        if (AutoClaim && !MR->getSymbols().count(InternedName)) {
           assert(!ExtraSymbolsToClaim.count(InternedName) &&
                  "Duplicate symbol to claim?");
           ExtraSymbolsToClaim[InternedName] = Flags;
@@ -134,7 +133,7 @@ public:
           Flags |= JITSymbolFlags::Weak;
         InternedResult[InternedName] =
             JITEvaluatedSymbol(Sym->getAddress(), Flags);
-        if (AutoClaim && !MR.getSymbols().count(InternedName)) {
+        if (AutoClaim && !MR->getSymbols().count(InternedName)) {
           assert(!ExtraSymbolsToClaim.count(InternedName) &&
                  "Duplicate symbol to claim?");
           ExtraSymbolsToClaim[InternedName] = Flags;
@@ -142,19 +141,19 @@ public:
       }
 
     if (!ExtraSymbolsToClaim.empty())
-      if (auto Err = MR.defineMaterializing(ExtraSymbolsToClaim))
-        return notifyFailed(std::move(Err));
+      if (auto Err = MR->defineMaterializing(ExtraSymbolsToClaim))
+        return Err;
 
     {
 
-      // Check that InternedResult matches up with MR.getSymbols().
+      // Check that InternedResult matches up with MR->getSymbols().
       // This guards against faulty transformations / compilers / object caches.
 
       // First check that there aren't any missing symbols.
       size_t NumMaterializationSideEffectsOnlySymbols = 0;
       SymbolNameVector ExtraSymbols;
       SymbolNameVector MissingSymbols;
-      for (auto &KV : MR.getSymbols()) {
+      for (auto &KV : MR->getSymbols()) {
 
         // If this is a materialization-side-effects only symbol then bump
         // the counter and make sure it's *not* defined, otherwise make
@@ -169,49 +168,42 @@ public:
       }
 
       // If there were missing symbols then report the error.
-      if (!MissingSymbols.empty()) {
-        ES.reportError(make_error<MissingSymbolDefinitions>(
-            G.getName(), std::move(MissingSymbols)));
-        MR.failMaterialization();
-        return;
-      }
+      if (!MissingSymbols.empty())
+        return make_error<MissingSymbolDefinitions>(G.getName(),
+                                                    std::move(MissingSymbols));
 
       // If there are more definitions than expected, add them to the
       // ExtraSymbols vector.
       if (InternedResult.size() >
-          MR.getSymbols().size() - NumMaterializationSideEffectsOnlySymbols) {
+          MR->getSymbols().size() - NumMaterializationSideEffectsOnlySymbols) {
         for (auto &KV : InternedResult)
-          if (!MR.getSymbols().count(KV.first))
+          if (!MR->getSymbols().count(KV.first))
             ExtraSymbols.push_back(KV.first);
       }
 
       // If there were extra definitions then report the error.
-      if (!ExtraSymbols.empty()) {
-        ES.reportError(make_error<UnexpectedSymbolDefinitions>(
-            G.getName(), std::move(ExtraSymbols)));
-        MR.failMaterialization();
-        return;
-      }
+      if (!ExtraSymbols.empty())
+        return make_error<UnexpectedSymbolDefinitions>(G.getName(),
+                                                       std::move(ExtraSymbols));
     }
 
-    if (auto Err = MR.notifyResolved(InternedResult)) {
-      Layer.getExecutionSession().reportError(std::move(Err));
-      MR.failMaterialization();
-      return;
-    }
-    Layer.notifyLoaded(MR);
+    if (auto Err = MR->notifyResolved(InternedResult))
+      return Err;
+
+    Layer.notifyLoaded(*MR);
+    return Error::success();
   }
 
   void notifyFinalized(
       std::unique_ptr<JITLinkMemoryManager::Allocation> A) override {
-    if (auto Err = Layer.notifyEmitted(MR, std::move(A))) {
+    if (auto Err = Layer.notifyEmitted(*MR, std::move(A))) {
       Layer.getExecutionSession().reportError(std::move(Err));
-      MR.failMaterialization();
+      MR->failMaterialization();
       return;
     }
-    if (auto Err = MR.notifyEmitted()) {
+    if (auto Err = MR->notifyEmitted()) {
       Layer.getExecutionSession().reportError(std::move(Err));
-      MR.failMaterialization();
+      MR->failMaterialization();
     }
   }
 
@@ -222,10 +214,11 @@ public:
   Error modifyPassConfig(const Triple &TT, PassConfiguration &Config) override {
     // Add passes to mark duplicate defs as should-discard, and to walk the
     // link graph to build the symbol dependence graph.
-    Config.PrePrunePasses.push_back(
-        [this](LinkGraph &G) { return externalizeWeakAndCommonSymbols(G); });
+    Config.PrePrunePasses.push_back([this](LinkGraph &G) {
+      return claimOrExternalizeWeakAndCommonSymbols(G);
+    });
 
-    Layer.modifyPassConfig(MR, TT, Config);
+    Layer.modifyPassConfig(*MR, TT, Config);
 
     Config.PostPrunePasses.push_back(
         [this](LinkGraph &G) { return computeNamedSymbolDependencies(G); });
@@ -241,19 +234,38 @@ private:
   using LocalSymbolNamedDependenciesMap =
       DenseMap<const Symbol *, LocalSymbolNamedDependencies>;
 
-  Error externalizeWeakAndCommonSymbols(LinkGraph &G) {
+  Error claimOrExternalizeWeakAndCommonSymbols(LinkGraph &G) {
     auto &ES = Layer.getExecutionSession();
-    for (auto *Sym : G.defined_symbols())
+
+    SymbolFlagsMap NewSymbolsToClaim;
+    std::vector<std::pair<SymbolStringPtr, Symbol *>> NameToSym;
+
+    auto ProcessSymbol = [&](Symbol *Sym) {
       if (Sym->hasName() && Sym->getLinkage() == Linkage::Weak) {
-        if (!MR.getSymbols().count(ES.intern(Sym->getName())))
-          G.makeExternal(*Sym);
+        auto Name = ES.intern(Sym->getName());
+        if (!MR->getSymbols().count(ES.intern(Sym->getName()))) {
+          JITSymbolFlags SF = JITSymbolFlags::Weak;
+          if (Sym->getScope() == Scope::Default)
+            SF |= JITSymbolFlags::Exported;
+          NewSymbolsToClaim[Name] = SF;
+          NameToSym.push_back(std::make_pair(std::move(Name), Sym));
+        }
       }
+    };
 
+    for (auto *Sym : G.defined_symbols())
+      ProcessSymbol(Sym);
     for (auto *Sym : G.absolute_symbols())
-      if (Sym->hasName() && Sym->getLinkage() == Linkage::Weak) {
-        if (!MR.getSymbols().count(ES.intern(Sym->getName())))
-          G.makeExternal(*Sym);
-      }
+      ProcessSymbol(Sym);
+
+    // Attempt to claim all weak defs that we're not already responsible for.
+    // This cannot fail -- any clashes will just result in rejection of our
+    // claim, at which point we'll externalize that symbol.
+    cantFail(MR->defineMaterializing(std::move(NewSymbolsToClaim)));
+
+    for (auto &KV : NameToSym)
+      if (!MR->getSymbols().count(KV.first))
+        G.makeExternal(*KV.second);
 
     return Error::success();
   }
@@ -261,13 +273,13 @@ private:
   Error markResponsibilitySymbolsLive(LinkGraph &G) const {
     auto &ES = Layer.getExecutionSession();
     for (auto *Sym : G.defined_symbols())
-      if (Sym->hasName() && MR.getSymbols().count(ES.intern(Sym->getName())))
+      if (Sym->hasName() && MR->getSymbols().count(ES.intern(Sym->getName())))
         Sym->setLive(true);
     return Error::success();
   }
 
   Error computeNamedSymbolDependencies(LinkGraph &G) {
-    auto &ES = MR.getTargetJITDylib().getExecutionSession();
+    auto &ES = MR->getTargetJITDylib().getExecutionSession();
     auto LocalDeps = computeLocalDeps(G);
 
     // Compute dependencies for symbols defined in the JITLink graph.
@@ -314,7 +326,7 @@ private:
     }
 
     for (auto &P : Layer.Plugins) {
-      auto SyntheticLocalDeps = P->getSyntheticSymbolLocalDependencies(MR);
+      auto SyntheticLocalDeps = P->getSyntheticSymbolLocalDependencies(*MR);
       if (SyntheticLocalDeps.empty())
         continue;
 
@@ -434,12 +446,12 @@ private:
           SymbolDeps.erase(&SourceJD);
       }
 
-      MR.addDependencies(Name, SymbolDeps);
+      MR->addDependencies(Name, SymbolDeps);
     }
   }
 
   ObjectLinkingLayer &Layer;
-  MaterializationResponsibility MR;
+  std::unique_ptr<MaterializationResponsibility> MR;
   std::unique_ptr<MemoryBuffer> ObjBuffer;
   DenseMap<SymbolStringPtr, SymbolNameSet> ExternalNamedSymbolDeps;
   DenseMap<SymbolStringPtr, SymbolNameSet> InternalNamedSymbolDeps;
@@ -447,20 +459,39 @@ private:
 
 ObjectLinkingLayer::Plugin::~Plugin() {}
 
+ObjectLinkingLayer::ObjectLinkingLayer(ExecutionSession &ES,
+                                       JITLinkMemoryManager &MemMgr)
+    : ObjectLayer(ES), MemMgr(MemMgr) {
+  ES.registerResourceManager(*this);
+}
+
 ObjectLinkingLayer::ObjectLinkingLayer(
     ExecutionSession &ES, std::unique_ptr<JITLinkMemoryManager> MemMgr)
-    : ObjectLayer(ES), MemMgr(std::move(MemMgr)) {}
+    : ObjectLayer(ES), MemMgr(*MemMgr), MemMgrOwnership(std::move(MemMgr)) {
+  ES.registerResourceManager(*this);
+}
 
 ObjectLinkingLayer::~ObjectLinkingLayer() {
-  if (auto Err = removeAllModules())
-    getExecutionSession().reportError(std::move(Err));
+  assert(Allocs.empty() && "Layer destroyed with resources still attached");
+  getExecutionSession().deregisterResourceManager(*this);
 }
 
-void ObjectLinkingLayer::emit(MaterializationResponsibility R,
+void ObjectLinkingLayer::emit(std::unique_ptr<MaterializationResponsibility> R,
                               std::unique_ptr<MemoryBuffer> O) {
   assert(O && "Object must not be null");
-  jitLink(std::make_unique<ObjectLinkingLayerJITLinkContext>(
-      *this, std::move(R), std::move(O)));
+  auto ObjBuffer = O->getMemBufferRef();
+  auto Ctx = std::make_unique<ObjectLinkingLayerJITLinkContext>(
+      *this, std::move(R), std::move(O));
+  if (auto G = createLinkGraphFromObject(std::move(ObjBuffer)))
+    link(std::move(*G), std::move(Ctx));
+  else
+    Ctx->notifyFailed(G.takeError());
+}
+
+void ObjectLinkingLayer::emit(std::unique_ptr<MaterializationResponsibility> R,
+                              std::unique_ptr<LinkGraph> G) {
+  link(std::move(G), std::make_unique<ObjectLinkingLayerJITLinkContext>(
+                         *this, std::move(R), nullptr));
 }
 
 void ObjectLinkingLayer::modifyPassConfig(MaterializationResponsibility &MR,
@@ -484,63 +515,56 @@ Error ObjectLinkingLayer::notifyEmitted(MaterializationResponsibility &MR,
   if (Err)
     return Err;
 
-  {
-    std::lock_guard<std::mutex> Lock(LayerMutex);
-    UntrackedAllocs.push_back(std::move(Alloc));
-  }
-
-  return Error::success();
+  return MR.withResourceKeyDo(
+      [&](ResourceKey K) { Allocs[K].push_back(std::move(Alloc)); });
 }
 
-Error ObjectLinkingLayer::removeModule(VModuleKey K) {
+Error ObjectLinkingLayer::handleRemoveResources(ResourceKey K) {
+
   Error Err = Error::success();
 
   for (auto &P : Plugins)
-    Err = joinErrors(std::move(Err), P->notifyRemovingModule(K));
+    Err = joinErrors(std::move(Err), P->notifyRemovingResources(K));
 
-  AllocPtr Alloc;
+  std::vector<AllocPtr> AllocsToRemove;
+  getExecutionSession().runSessionLocked([&] {
+    auto I = Allocs.find(K);
+    if (I != Allocs.end()) {
+      std::swap(AllocsToRemove, I->second);
+      Allocs.erase(I);
+    }
+  });
 
-  {
-    std::lock_guard<std::mutex> Lock(LayerMutex);
-    auto AllocItr = TrackedAllocs.find(K);
-    Alloc = std::move(AllocItr->second);
-    TrackedAllocs.erase(AllocItr);
+  while (!AllocsToRemove.empty()) {
+    Err = joinErrors(std::move(Err), AllocsToRemove.back()->deallocate());
+    AllocsToRemove.pop_back();
   }
 
-  assert(Alloc && "No allocation for key K");
-
-  return joinErrors(std::move(Err), Alloc->deallocate());
+  return Err;
 }
 
-Error ObjectLinkingLayer::removeAllModules() {
+void ObjectLinkingLayer::handleTransferResources(ResourceKey DstKey,
+                                                 ResourceKey SrcKey) {
+  auto I = Allocs.find(SrcKey);
+  if (I != Allocs.end()) {
+    auto &SrcAllocs = I->second;
+    auto &DstAllocs = Allocs[DstKey];
+    DstAllocs.reserve(DstAllocs.size() + SrcAllocs.size());
+    for (auto &Alloc : SrcAllocs)
+      DstAllocs.push_back(std::move(Alloc));
 
-  Error Err = Error::success();
-
-  for (auto &P : Plugins)
-    Err = joinErrors(std::move(Err), P->notifyRemovingAllModules());
-
-  std::vector<AllocPtr> Allocs;
-  {
-    std::lock_guard<std::mutex> Lock(LayerMutex);
-    Allocs = std::move(UntrackedAllocs);
-
-    for (auto &KV : TrackedAllocs)
-      Allocs.push_back(std::move(KV.second));
-
-    TrackedAllocs.clear();
-  }
-
-  while (!Allocs.empty()) {
-    Err = joinErrors(std::move(Err), Allocs.back()->deallocate());
-    Allocs.pop_back();
+    // Erase SrcKey entry using value rather than iterator I: I may have been
+    // invalidated when we looked up DstKey.
+    Allocs.erase(SrcKey);
   }
 
-  return Err;
+  for (auto &P : Plugins)
+    P->notifyTransferringResources(DstKey, SrcKey);
 }
 
 EHFrameRegistrationPlugin::EHFrameRegistrationPlugin(
-    EHFrameRegistrar &Registrar)
-    : Registrar(Registrar) {}
+    ExecutionSession &ES, std::unique_ptr<EHFrameRegistrar> Registrar)
+    : ES(ES), Registrar(std::move(Registrar)) {}
 
 void EHFrameRegistrationPlugin::modifyPassConfig(
     MaterializationResponsibility &MR, const Triple &TT,
@@ -559,65 +583,70 @@ void EHFrameRegistrationPlugin::modifyPassConfig(
 
 Error EHFrameRegistrationPlugin::notifyEmitted(
     MaterializationResponsibility &MR) {
-  std::lock_guard<std::mutex> Lock(EHFramePluginMutex);
-
-  auto EHFrameRangeItr = InProcessLinks.find(&MR);
-  if (EHFrameRangeItr == InProcessLinks.end())
-    return Error::success();
-
-  auto EHFrameRange = EHFrameRangeItr->second;
-  assert(EHFrameRange.Addr &&
-         "eh-frame addr to register can not be null");
-
-  InProcessLinks.erase(EHFrameRangeItr);
-  if (auto Key = MR.getVModuleKey())
-    TrackedEHFrameRanges[Key] = EHFrameRange;
-  else
-    UntrackedEHFrameRanges.push_back(EHFrameRange);
 
-  return Registrar.registerEHFrames(EHFrameRange.Addr, EHFrameRange.Size);
-}
-
-Error EHFrameRegistrationPlugin::notifyRemovingModule(VModuleKey K) {
-  std::lock_guard<std::mutex> Lock(EHFramePluginMutex);
+  EHFrameRange EmittedRange;
+  {
+    std::lock_guard<std::mutex> Lock(EHFramePluginMutex);
 
-  auto EHFrameRangeItr = TrackedEHFrameRanges.find(K);
-  if (EHFrameRangeItr == TrackedEHFrameRanges.end())
-    return Error::success();
+    auto EHFrameRangeItr = InProcessLinks.find(&MR);
+    if (EHFrameRangeItr == InProcessLinks.end())
+      return Error::success();
 
-  auto EHFrameRange = EHFrameRangeItr->second;
-  assert(EHFrameRange.Addr && "Tracked eh-frame range must not be null");
+    EmittedRange = EHFrameRangeItr->second;
+    assert(EmittedRange.Addr && "eh-frame addr to register can not be null");
+    InProcessLinks.erase(EHFrameRangeItr);
+  }
 
-  TrackedEHFrameRanges.erase(EHFrameRangeItr);
+  if (auto Err = MR.withResourceKeyDo(
+          [&](ResourceKey K) { EHFrameRanges[K].push_back(EmittedRange); }))
+    return Err;
 
-  return Registrar.deregisterEHFrames(EHFrameRange.Addr, EHFrameRange.Size);
+  return Registrar->registerEHFrames(EmittedRange.Addr, EmittedRange.Size);
 }
 
-Error EHFrameRegistrationPlugin::notifyRemovingAllModules() {
+Error EHFrameRegistrationPlugin::notifyFailed(
+    MaterializationResponsibility &MR) {
   std::lock_guard<std::mutex> Lock(EHFramePluginMutex);
+  InProcessLinks.erase(&MR);
+  return Error::success();
+}
 
-  std::vector<EHFrameRange> EHFrameRanges =
-    std::move(UntrackedEHFrameRanges);
-  EHFrameRanges.reserve(EHFrameRanges.size() + TrackedEHFrameRanges.size());
-
-  for (auto &KV : TrackedEHFrameRanges)
-    EHFrameRanges.push_back(KV.second);
+Error EHFrameRegistrationPlugin::notifyRemovingResources(ResourceKey K) {
+  std::vector<EHFrameRange> RangesToRemove;
 
-  TrackedEHFrameRanges.clear();
+  ES.runSessionLocked([&] {
+    auto I = EHFrameRanges.find(K);
+    if (I != EHFrameRanges.end()) {
+      RangesToRemove = std::move(I->second);
+      EHFrameRanges.erase(I);
+    }
+  });
 
   Error Err = Error::success();
-
-  while (!EHFrameRanges.empty()) {
-    auto EHFrameRange = EHFrameRanges.back();
-    assert(EHFrameRange.Addr && "Untracked eh-frame range must not be null");
-    EHFrameRanges.pop_back();
-    Err = joinErrors(std::move(Err),
-                     Registrar.deregisterEHFrames(EHFrameRange.Addr,
-                                                  EHFrameRange.Size));
+  while (!RangesToRemove.empty()) {
+    auto RangeToRemove = RangesToRemove.back();
+    RangesToRemove.pop_back();
+    assert(RangeToRemove.Addr && "Untracked eh-frame range must not be null");
+    Err = joinErrors(
+        std::move(Err),
+        Registrar->deregisterEHFrames(RangeToRemove.Addr, RangeToRemove.Size));
   }
 
   return Err;
 }
 
+void EHFrameRegistrationPlugin::notifyTransferringResources(
+    ResourceKey DstKey, ResourceKey SrcKey) {
+  auto SI = EHFrameRanges.find(SrcKey);
+  if (SI != EHFrameRanges.end()) {
+    auto &SrcRanges = SI->second;
+    auto &DstRanges = EHFrameRanges[DstKey];
+    DstRanges.reserve(DstRanges.size() + SrcRanges.size());
+    for (auto &SrcRange : SrcRanges)
+      DstRanges.push_back(std::move(SrcRange));
+    EHFrameRanges.erase(SI);
+  }
+}
+
 } // End namespace orc.
 } // End namespace llvm.
diff --git a/llvm/lib/ExecutionEngine/Orc/ObjectTransformLayer.cpp b/llvm/lib/ExecutionEngine/Orc/ObjectTransformLayer.cpp
index d18eb38a4142..a57662e10a79 100644
--- a/llvm/lib/ExecutionEngine/Orc/ObjectTransformLayer.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/ObjectTransformLayer.cpp
@@ -17,8 +17,9 @@ ObjectTransformLayer::ObjectTransformLayer(ExecutionSession &ES,
                                             TransformFunction Transform)
     : ObjectLayer(ES), BaseLayer(BaseLayer), Transform(std::move(Transform)) {}
 
-void ObjectTransformLayer::emit(MaterializationResponsibility R,
-                                std::unique_ptr<MemoryBuffer> O) {
+void ObjectTransformLayer::emit(
+    std::unique_ptr<MaterializationResponsibility> R,
+    std::unique_ptr<MemoryBuffer> O) {
   assert(O && "Module must not be null");
 
   // If there is a transform set then apply it.
@@ -26,7 +27,7 @@ void ObjectTransformLayer::emit(MaterializationResponsibility R,
     if (auto TransformedObj = Transform(std::move(O)))
       O = std::move(*TransformedObj);
     else {
-      R.failMaterialization();
+      R->failMaterialization();
       getExecutionSession().reportError(TransformedObj.takeError());
       return;
     }
diff --git a/llvm/lib/ExecutionEngine/Orc/OrcCBindings.cpp b/llvm/lib/ExecutionEngine/Orc/OrcCBindings.cpp
deleted file mode 100644
index 28c8479abba4..000000000000
--- a/llvm/lib/ExecutionEngine/Orc/OrcCBindings.cpp
+++ /dev/null
@@ -1,158 +0,0 @@
-//===----------- OrcCBindings.cpp - C bindings for the Orc APIs -----------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#include "OrcCBindingsStack.h"
-#include "llvm-c/OrcBindings.h"
-#include "llvm/ExecutionEngine/JITEventListener.h"
-
-using namespace llvm;
-
-LLVMOrcJITStackRef LLVMOrcCreateInstance(LLVMTargetMachineRef TM) {
-  TargetMachine *TM2(unwrap(TM));
-
-  Triple T(TM2->getTargetTriple());
-
-  auto IndirectStubsMgrBuilder =
-      orc::createLocalIndirectStubsManagerBuilder(T);
-
-  OrcCBindingsStack *JITStack =
-      new OrcCBindingsStack(*TM2, std::move(IndirectStubsMgrBuilder));
-
-  return wrap(JITStack);
-}
-
-const char *LLVMOrcGetErrorMsg(LLVMOrcJITStackRef JITStack) {
-  OrcCBindingsStack &J = *unwrap(JITStack);
-  return J.getErrorMessage().c_str();
-}
-
-void LLVMOrcGetMangledSymbol(LLVMOrcJITStackRef JITStack, char **MangledName,
-                             const char *SymbolName) {
-  OrcCBindingsStack &J = *unwrap(JITStack);
-  std::string Mangled = J.mangle(SymbolName);
-  *MangledName = new char[Mangled.size() + 1];
-  strcpy(*MangledName, Mangled.c_str());
-}
-
-void LLVMOrcDisposeMangledSymbol(char *MangledName) { delete[] MangledName; }
-
-LLVMErrorRef LLVMOrcCreateLazyCompileCallback(
-    LLVMOrcJITStackRef JITStack, LLVMOrcTargetAddress *RetAddr,
-    LLVMOrcLazyCompileCallbackFn Callback, void *CallbackCtx) {
-  OrcCBindingsStack &J = *unwrap(JITStack);
-  if (auto Addr = J.createLazyCompileCallback(Callback, CallbackCtx)) {
-    *RetAddr = *Addr;
-    return LLVMErrorSuccess;
-  } else
-    return wrap(Addr.takeError());
-}
-
-LLVMErrorRef LLVMOrcCreateIndirectStub(LLVMOrcJITStackRef JITStack,
-                                       const char *StubName,
-                                       LLVMOrcTargetAddress InitAddr) {
-  OrcCBindingsStack &J = *unwrap(JITStack);
-  return wrap(J.createIndirectStub(StubName, InitAddr));
-}
-
-LLVMErrorRef LLVMOrcSetIndirectStubPointer(LLVMOrcJITStackRef JITStack,
-                                           const char *StubName,
-                                           LLVMOrcTargetAddress NewAddr) {
-  OrcCBindingsStack &J = *unwrap(JITStack);
-  return wrap(J.setIndirectStubPointer(StubName, NewAddr));
-}
-
-LLVMErrorRef LLVMOrcAddEagerlyCompiledIR(LLVMOrcJITStackRef JITStack,
-                                         LLVMOrcModuleHandle *RetHandle,
-                                         LLVMModuleRef Mod,
-                                         LLVMOrcSymbolResolverFn SymbolResolver,
-                                         void *SymbolResolverCtx) {
-  OrcCBindingsStack &J = *unwrap(JITStack);
-  std::unique_ptr<Module> M(unwrap(Mod));
-  if (auto Handle =
-          J.addIRModuleEager(std::move(M), SymbolResolver, SymbolResolverCtx)) {
-    *RetHandle = *Handle;
-    return LLVMErrorSuccess;
-  } else
-    return wrap(Handle.takeError());
-}
-
-LLVMErrorRef LLVMOrcAddLazilyCompiledIR(LLVMOrcJITStackRef JITStack,
-                                        LLVMOrcModuleHandle *RetHandle,
-                                        LLVMModuleRef Mod,
-                                        LLVMOrcSymbolResolverFn SymbolResolver,
-                                        void *SymbolResolverCtx) {
-  OrcCBindingsStack &J = *unwrap(JITStack);
-  std::unique_ptr<Module> M(unwrap(Mod));
-  if (auto Handle =
-          J.addIRModuleLazy(std::move(M), SymbolResolver, SymbolResolverCtx)) {
-    *RetHandle = *Handle;
-    return LLVMErrorSuccess;
-  } else
-    return wrap(Handle.takeError());
-}
-
-LLVMErrorRef LLVMOrcAddObjectFile(LLVMOrcJITStackRef JITStack,
-                                  LLVMOrcModuleHandle *RetHandle,
-                                  LLVMMemoryBufferRef Obj,
-                                  LLVMOrcSymbolResolverFn SymbolResolver,
-                                  void *SymbolResolverCtx) {
-  OrcCBindingsStack &J = *unwrap(JITStack);
-  std::unique_ptr<MemoryBuffer> O(unwrap(Obj));
-  if (auto Handle =
-          J.addObject(std::move(O), SymbolResolver, SymbolResolverCtx)) {
-    *RetHandle = *Handle;
-    return LLVMErrorSuccess;
-  } else
-    return wrap(Handle.takeError());
-}
-
-LLVMErrorRef LLVMOrcRemoveModule(LLVMOrcJITStackRef JITStack,
-                                 LLVMOrcModuleHandle H) {
-  OrcCBindingsStack &J = *unwrap(JITStack);
-  return wrap(J.removeModule(H));
-}
-
-LLVMErrorRef LLVMOrcGetSymbolAddress(LLVMOrcJITStackRef JITStack,
-                                     LLVMOrcTargetAddress *RetAddr,
-                                     const char *SymbolName) {
-  OrcCBindingsStack &J = *unwrap(JITStack);
-  if (auto Addr = J.findSymbolAddress(SymbolName, true)) {
-    *RetAddr = *Addr;
-    return LLVMErrorSuccess;
-  } else
-    return wrap(Addr.takeError());
-}
-
-LLVMErrorRef LLVMOrcGetSymbolAddressIn(LLVMOrcJITStackRef JITStack,
-                                       LLVMOrcTargetAddress *RetAddr,
-                                       LLVMOrcModuleHandle H,
-                                       const char *SymbolName) {
-  OrcCBindingsStack &J = *unwrap(JITStack);
-  if (auto Addr = J.findSymbolAddressIn(H, SymbolName, true)) {
-    *RetAddr = *Addr;
-    return LLVMErrorSuccess;
-  } else
-    return wrap(Addr.takeError());
-}
-
-LLVMErrorRef LLVMOrcDisposeInstance(LLVMOrcJITStackRef JITStack) {
-  auto *J = unwrap(JITStack);
-  auto Err = J->shutdown();
-  delete J;
-  return wrap(std::move(Err));
-}
-
-void LLVMOrcRegisterJITEventListener(LLVMOrcJITStackRef JITStack, LLVMJITEventListenerRef L)
-{
-  unwrap(JITStack)->RegisterJITEventListener(unwrap(L));
-}
-
-void LLVMOrcUnregisterJITEventListener(LLVMOrcJITStackRef JITStack, LLVMJITEventListenerRef L)
-{
-  unwrap(JITStack)->UnregisterJITEventListener(unwrap(L));
-}
diff --git a/llvm/lib/ExecutionEngine/Orc/OrcCBindingsStack.h b/llvm/lib/ExecutionEngine/Orc/OrcCBindingsStack.h
deleted file mode 100644
index 87bb4398765d..000000000000
--- a/llvm/lib/ExecutionEngine/Orc/OrcCBindingsStack.h
+++ /dev/null
@@ -1,534 +0,0 @@
-//===- OrcCBindingsStack.h - Orc JIT stack for C bindings -----*- C++ -*---===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_LIB_EXECUTIONENGINE_ORC_ORCCBINDINGSSTACK_H
-#define LLVM_LIB_EXECUTIONENGINE_ORC_ORCCBINDINGSSTACK_H
-
-#include "llvm-c/OrcBindings.h"
-#include "llvm-c/TargetMachine.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/ADT/StringRef.h"
-#include "llvm/ExecutionEngine/JITSymbol.h"
-#include "llvm/ExecutionEngine/JITEventListener.h"
-#include "llvm/ExecutionEngine/Orc/CompileOnDemandLayer.h"
-#include "llvm/ExecutionEngine/Orc/CompileUtils.h"
-#include "llvm/ExecutionEngine/Orc/ExecutionUtils.h"
-#include "llvm/ExecutionEngine/Orc/IRCompileLayer.h"
-#include "llvm/ExecutionEngine/Orc/LambdaResolver.h"
-#include "llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h"
-#include "llvm/ExecutionEngine/RuntimeDyld.h"
-#include "llvm/ExecutionEngine/SectionMemoryManager.h"
-#include "llvm/IR/DataLayout.h"
-#include "llvm/IR/Mangler.h"
-#include "llvm/IR/Module.h"
-#include "llvm/Support/CBindingWrapping.h"
-#include "llvm/Support/Error.h"
-#include "llvm/Support/raw_ostream.h"
-#include "llvm/Target/TargetMachine.h"
-#include <algorithm>
-#include <cstdint>
-#include <functional>
-#include <map>
-#include <memory>
-#include <set>
-#include <string>
-#include <vector>
-
-namespace llvm {
-
-class OrcCBindingsStack;
-
-DEFINE_SIMPLE_CONVERSION_FUNCTIONS(OrcCBindingsStack, LLVMOrcJITStackRef)
-DEFINE_SIMPLE_CONVERSION_FUNCTIONS(TargetMachine, LLVMTargetMachineRef)
-
-namespace detail {
-
-// FIXME: Kill this off once the Layer concept becomes an interface.
-class GenericLayer {
-public:
-  virtual ~GenericLayer() = default;
-
-  virtual JITSymbol findSymbolIn(orc::VModuleKey K, const std::string &Name,
-                                 bool ExportedSymbolsOnly) = 0;
-  virtual Error removeModule(orc::VModuleKey K) = 0;
-  };
-
-  template <typename LayerT> class GenericLayerImpl : public GenericLayer {
-  public:
-    GenericLayerImpl(LayerT &Layer) : Layer(Layer) {}
-
-    JITSymbol findSymbolIn(orc::VModuleKey K, const std::string &Name,
-                           bool ExportedSymbolsOnly) override {
-      return Layer.findSymbolIn(K, Name, ExportedSymbolsOnly);
-    }
-
-    Error removeModule(orc::VModuleKey K) override {
-      return Layer.removeModule(K);
-    }
-
-  private:
-    LayerT &Layer;
-  };
-
-  template <>
-  class GenericLayerImpl<orc::LegacyRTDyldObjectLinkingLayer> : public GenericLayer {
-  private:
-    using LayerT = orc::LegacyRTDyldObjectLinkingLayer;
-  public:
-    GenericLayerImpl(LayerT &Layer) : Layer(Layer) {}
-
-    JITSymbol findSymbolIn(orc::VModuleKey K, const std::string &Name,
-                           bool ExportedSymbolsOnly) override {
-      return Layer.findSymbolIn(K, Name, ExportedSymbolsOnly);
-    }
-
-    Error removeModule(orc::VModuleKey K) override {
-      return Layer.removeObject(K);
-    }
-
-  private:
-    LayerT &Layer;
-  };
-
-  template <typename LayerT>
-  std::unique_ptr<GenericLayerImpl<LayerT>> createGenericLayer(LayerT &Layer) {
-    return std::make_unique<GenericLayerImpl<LayerT>>(Layer);
-  }
-
-} // end namespace detail
-
-class OrcCBindingsStack {
-public:
-
-  using CompileCallbackMgr = orc::JITCompileCallbackManager;
-  using ObjLayerT = orc::LegacyRTDyldObjectLinkingLayer;
-  using CompileLayerT = orc::LegacyIRCompileLayer<ObjLayerT, orc::SimpleCompiler>;
-  using CODLayerT =
-        orc::LegacyCompileOnDemandLayer<CompileLayerT, CompileCallbackMgr>;
-
-  using CallbackManagerBuilder =
-      std::function<std::unique_ptr<CompileCallbackMgr>()>;
-
-  using IndirectStubsManagerBuilder = CODLayerT::IndirectStubsManagerBuilderT;
-
-private:
-
-  using OwningObject = object::OwningBinary<object::ObjectFile>;
-
-  class CBindingsResolver : public orc::SymbolResolver {
-  public:
-    CBindingsResolver(OrcCBindingsStack &Stack,
-                      LLVMOrcSymbolResolverFn ExternalResolver,
-                      void *ExternalResolverCtx)
-        : Stack(Stack), ExternalResolver(std::move(ExternalResolver)),
-          ExternalResolverCtx(std::move(ExternalResolverCtx)) {}
-
-    orc::SymbolNameSet
-    getResponsibilitySet(const orc::SymbolNameSet &Symbols) override {
-      orc::SymbolNameSet Result;
-
-      for (auto &S : Symbols) {
-        if (auto Sym = findSymbol(std::string(*S))) {
-          if (!Sym.getFlags().isStrong())
-            Result.insert(S);
-        } else if (auto Err = Sym.takeError()) {
-          Stack.reportError(std::move(Err));
-          return orc::SymbolNameSet();
-        }
-      }
-
-      return Result;
-    }
-
-    orc::SymbolNameSet
-    lookup(std::shared_ptr<orc::AsynchronousSymbolQuery> Query,
-           orc::SymbolNameSet Symbols) override {
-      orc::SymbolNameSet UnresolvedSymbols;
-
-      for (auto &S : Symbols) {
-        if (auto Sym = findSymbol(std::string(*S))) {
-          if (auto Addr = Sym.getAddress()) {
-            Query->notifySymbolMetRequiredState(
-                S, JITEvaluatedSymbol(*Addr, Sym.getFlags()));
-          } else {
-            Stack.ES.legacyFailQuery(*Query, Addr.takeError());
-            return orc::SymbolNameSet();
-          }
-        } else if (auto Err = Sym.takeError()) {
-          Stack.ES.legacyFailQuery(*Query, std::move(Err));
-          return orc::SymbolNameSet();
-        } else
-          UnresolvedSymbols.insert(S);
-      }
-
-      if (Query->isComplete())
-        Query->handleComplete();
-
-      return UnresolvedSymbols;
-    }
-
-  private:
-    JITSymbol findSymbol(const std::string &Name) {
-      // Search order:
-      // 1. JIT'd symbols.
-      // 2. Runtime overrides.
-      // 3. External resolver (if present).
-
-      if (Stack.CODLayer) {
-        if (auto Sym = Stack.CODLayer->findSymbol(Name, true))
-          return Sym;
-        else if (auto Err = Sym.takeError())
-          return Sym.takeError();
-      } else {
-        if (auto Sym = Stack.CompileLayer.findSymbol(Name, true))
-          return Sym;
-        else if (auto Err = Sym.takeError())
-          return Sym.takeError();
-      }
-
-      if (auto Sym = Stack.CXXRuntimeOverrides.searchOverrides(Name))
-        return Sym;
-
-      if (ExternalResolver)
-        return JITSymbol(ExternalResolver(Name.c_str(), ExternalResolverCtx),
-                         JITSymbolFlags::Exported);
-
-      return JITSymbol(nullptr);
-    }
-
-    OrcCBindingsStack &Stack;
-    LLVMOrcSymbolResolverFn ExternalResolver;
-    void *ExternalResolverCtx = nullptr;
-  };
-
-public:
-  OrcCBindingsStack(TargetMachine &TM,
-                    IndirectStubsManagerBuilder IndirectStubsMgrBuilder)
-      : CCMgr(createCompileCallbackManager(TM, ES)), DL(TM.createDataLayout()),
-        IndirectStubsMgr(IndirectStubsMgrBuilder()),
-        ObjectLayer(
-            AcknowledgeORCv1Deprecation, ES,
-            [this](orc::VModuleKey K) {
-              auto ResolverI = Resolvers.find(K);
-              assert(ResolverI != Resolvers.end() &&
-                     "No resolver for module K");
-              auto Resolver = std::move(ResolverI->second);
-              Resolvers.erase(ResolverI);
-              return ObjLayerT::Resources{
-                  std::make_shared<SectionMemoryManager>(), Resolver};
-            },
-            nullptr,
-            [this](orc::VModuleKey K, const object::ObjectFile &Obj,
-                   const RuntimeDyld::LoadedObjectInfo &LoadedObjInfo) {
-              this->notifyFinalized(K, Obj, LoadedObjInfo);
-            },
-            [this](orc::VModuleKey K, const object::ObjectFile &Obj) {
-              this->notifyFreed(K, Obj);
-            }),
-        CompileLayer(AcknowledgeORCv1Deprecation, ObjectLayer,
-                     orc::SimpleCompiler(TM)),
-        CODLayer(createCODLayer(ES, CompileLayer, CCMgr.get(),
-                                std::move(IndirectStubsMgrBuilder), Resolvers)),
-        CXXRuntimeOverrides(
-            AcknowledgeORCv1Deprecation,
-            [this](const std::string &S) { return mangle(S); }) {}
-
-  Error shutdown() {
-    // Run any destructors registered with __cxa_atexit.
-    CXXRuntimeOverrides.runDestructors();
-    // Run any IR destructors.
-    for (auto &DtorRunner : IRStaticDestructorRunners)
-      if (auto Err = DtorRunner.runViaLayer(*this))
-        return Err;
-    return Error::success();
-  }
-
-  std::string mangle(StringRef Name) {
-    std::string MangledName;
-    {
-      raw_string_ostream MangledNameStream(MangledName);
-      Mangler::getNameWithPrefix(MangledNameStream, Name, DL);
-    }
-    return MangledName;
-  }
-
-  template <typename PtrTy>
-  static PtrTy fromTargetAddress(JITTargetAddress Addr) {
-    return reinterpret_cast<PtrTy>(static_cast<uintptr_t>(Addr));
-  }
-
-  Expected<JITTargetAddress>
-  createLazyCompileCallback(LLVMOrcLazyCompileCallbackFn Callback,
-                            void *CallbackCtx) {
-    auto WrappedCallback = [=]() -> JITTargetAddress {
-      return Callback(wrap(this), CallbackCtx);
-    };
-
-    return CCMgr->getCompileCallback(std::move(WrappedCallback));
-  }
-
-  Error createIndirectStub(StringRef StubName, JITTargetAddress Addr) {
-    return IndirectStubsMgr->createStub(StubName, Addr,
-                                        JITSymbolFlags::Exported);
-  }
-
-  Error setIndirectStubPointer(StringRef Name, JITTargetAddress Addr) {
-    return IndirectStubsMgr->updatePointer(Name, Addr);
-  }
-
-  template <typename LayerT>
-  Expected<orc::VModuleKey>
-  addIRModule(LayerT &Layer, std::unique_ptr<Module> M,
-              std::unique_ptr<RuntimeDyld::MemoryManager> MemMgr,
-              LLVMOrcSymbolResolverFn ExternalResolver,
-              void *ExternalResolverCtx) {
-
-    // Attach a data-layout if one isn't already present.
-    if (M->getDataLayout().isDefault())
-      M->setDataLayout(DL);
-
-    // Record the static constructors and destructors. We have to do this before
-    // we hand over ownership of the module to the JIT.
-    std::vector<std::string> CtorNames, DtorNames;
-    for (auto Ctor : orc::getConstructors(*M))
-      CtorNames.push_back(mangle(Ctor.Func->getName()));
-    for (auto Dtor : orc::getDestructors(*M))
-      DtorNames.push_back(mangle(Dtor.Func->getName()));
-
-    // Add the module to the JIT.
-    auto K = ES.allocateVModule();
-    Resolvers[K] = std::make_shared<CBindingsResolver>(*this, ExternalResolver,
-                                                       ExternalResolverCtx);
-    if (auto Err = Layer.addModule(K, std::move(M)))
-      return std::move(Err);
-
-    KeyLayers[K] = detail::createGenericLayer(Layer);
-
-    // Run the static constructors, and save the static destructor runner for
-    // execution when the JIT is torn down.
-    orc::LegacyCtorDtorRunner<OrcCBindingsStack> CtorRunner(
-        AcknowledgeORCv1Deprecation, std::move(CtorNames), K);
-    if (auto Err = CtorRunner.runViaLayer(*this))
-      return std::move(Err);
-
-    IRStaticDestructorRunners.emplace_back(AcknowledgeORCv1Deprecation,
-                                           std::move(DtorNames), K);
-
-    return K;
-  }
-
-  Expected<orc::VModuleKey>
-  addIRModuleEager(std::unique_ptr<Module> M,
-                   LLVMOrcSymbolResolverFn ExternalResolver,
-                   void *ExternalResolverCtx) {
-    return addIRModule(CompileLayer, std::move(M),
-                       std::make_unique<SectionMemoryManager>(),
-                       std::move(ExternalResolver), ExternalResolverCtx);
-  }
-
-  Expected<orc::VModuleKey>
-  addIRModuleLazy(std::unique_ptr<Module> M,
-                  LLVMOrcSymbolResolverFn ExternalResolver,
-                  void *ExternalResolverCtx) {
-    if (!CODLayer)
-      return make_error<StringError>("Can not add lazy module: No compile "
-                                     "callback manager available",
-                                     inconvertibleErrorCode());
-
-    return addIRModule(*CODLayer, std::move(M),
-                       std::make_unique<SectionMemoryManager>(),
-                       std::move(ExternalResolver), ExternalResolverCtx);
-  }
-
-  Error removeModule(orc::VModuleKey K) {
-    // FIXME: Should error release the module key?
-    if (auto Err = KeyLayers[K]->removeModule(K))
-      return Err;
-    ES.releaseVModule(K);
-    KeyLayers.erase(K);
-    return Error::success();
-  }
-
-  Expected<orc::VModuleKey> addObject(std::unique_ptr<MemoryBuffer> ObjBuffer,
-                                      LLVMOrcSymbolResolverFn ExternalResolver,
-                                      void *ExternalResolverCtx) {
-    if (auto Obj = object::ObjectFile::createObjectFile(
-            ObjBuffer->getMemBufferRef())) {
-
-      auto K = ES.allocateVModule();
-      Resolvers[K] = std::make_shared<CBindingsResolver>(
-          *this, ExternalResolver, ExternalResolverCtx);
-
-      if (auto Err = ObjectLayer.addObject(K, std::move(ObjBuffer)))
-        return std::move(Err);
-
-      KeyLayers[K] = detail::createGenericLayer(ObjectLayer);
-
-      return K;
-    } else
-      return Obj.takeError();
-  }
-
-  JITSymbol findSymbol(const std::string &Name,
-                                 bool ExportedSymbolsOnly) {
-    if (auto Sym = IndirectStubsMgr->findStub(Name, ExportedSymbolsOnly))
-      return Sym;
-    if (CODLayer)
-      return CODLayer->findSymbol(mangle(Name), ExportedSymbolsOnly);
-    return CompileLayer.findSymbol(mangle(Name), ExportedSymbolsOnly);
-  }
-
-  JITSymbol findSymbolIn(orc::VModuleKey K, const std::string &Name,
-                         bool ExportedSymbolsOnly) {
-    assert(KeyLayers.count(K) && "looking up symbol in unknown module");
-    return KeyLayers[K]->findSymbolIn(K, mangle(Name), ExportedSymbolsOnly);
-  }
-
-  Expected<JITTargetAddress> findSymbolAddress(const std::string &Name,
-                                               bool ExportedSymbolsOnly) {
-    if (auto Sym = findSymbol(Name, ExportedSymbolsOnly)) {
-      // Successful lookup, non-null symbol:
-      if (auto AddrOrErr = Sym.getAddress())
-        return *AddrOrErr;
-      else
-        return AddrOrErr.takeError();
-    } else if (auto Err = Sym.takeError()) {
-      // Lookup failure - report error.
-      return std::move(Err);
-    }
-
-    // No symbol not found. Return 0.
-    return 0;
-  }
-
-  Expected<JITTargetAddress> findSymbolAddressIn(orc::VModuleKey K,
-                                                 const std::string &Name,
-                                                 bool ExportedSymbolsOnly) {
-    if (auto Sym = findSymbolIn(K, Name, ExportedSymbolsOnly)) {
-      // Successful lookup, non-null symbol:
-      if (auto AddrOrErr = Sym.getAddress())
-        return *AddrOrErr;
-      else
-        return AddrOrErr.takeError();
-    } else if (auto Err = Sym.takeError()) {
-      // Lookup failure - report error.
-      return std::move(Err);
-    }
-
-    // Symbol not found. Return 0.
-    return 0;
-  }
-
-  const std::string &getErrorMessage() const { return ErrMsg; }
-
-  void RegisterJITEventListener(JITEventListener *L) {
-    if (!L)
-      return;
-    EventListeners.push_back(L);
-  }
-
-  void UnregisterJITEventListener(JITEventListener *L) {
-    if (!L)
-      return;
-
-    auto I = find(reverse(EventListeners), L);
-    if (I != EventListeners.rend()) {
-      std::swap(*I, EventListeners.back());
-      EventListeners.pop_back();
-    }
-  }
-
-private:
-  using ResolverMap =
-      std::map<orc::VModuleKey, std::shared_ptr<orc::SymbolResolver>>;
-
-  static std::unique_ptr<CompileCallbackMgr>
-  createCompileCallbackManager(TargetMachine &TM, orc::ExecutionSession &ES) {
-    auto CCMgr = createLocalCompileCallbackManager(TM.getTargetTriple(), ES, 0);
-    if (!CCMgr) {
-      // FIXME: It would be good if we could report this somewhere, but we do
-      //        have an instance yet.
-      logAllUnhandledErrors(CCMgr.takeError(), errs(), "ORC error: ");
-      return nullptr;
-    }
-    return std::move(*CCMgr);
-  }
-
-  static std::unique_ptr<CODLayerT>
-  createCODLayer(orc::ExecutionSession &ES, CompileLayerT &CompileLayer,
-                 CompileCallbackMgr *CCMgr,
-                 IndirectStubsManagerBuilder IndirectStubsMgrBuilder,
-                 ResolverMap &Resolvers) {
-    // If there is no compile callback manager available we can not create a
-    // compile on demand layer.
-    if (!CCMgr)
-      return nullptr;
-
-    return std::make_unique<CODLayerT>(
-        AcknowledgeORCv1Deprecation, ES, CompileLayer,
-        [&Resolvers](orc::VModuleKey K) {
-          auto ResolverI = Resolvers.find(K);
-          assert(ResolverI != Resolvers.end() && "No resolver for module K");
-          return ResolverI->second;
-        },
-        [&Resolvers](orc::VModuleKey K,
-                     std::shared_ptr<orc::SymbolResolver> Resolver) {
-          assert(!Resolvers.count(K) && "Resolver already present");
-          Resolvers[K] = std::move(Resolver);
-        },
-        [](Function &F) { return std::set<Function *>({&F}); }, *CCMgr,
-        std::move(IndirectStubsMgrBuilder), false);
-  }
-
-  void reportError(Error Err) {
-    // FIXME: Report errors on the execution session.
-    logAllUnhandledErrors(std::move(Err), errs(), "ORC error: ");
-  };
-
-  void notifyFinalized(orc::VModuleKey K,
-		       const object::ObjectFile &Obj,
-		       const RuntimeDyld::LoadedObjectInfo &LoadedObjInfo) {
-    uint64_t Key = static_cast<uint64_t>(
-        reinterpret_cast<uintptr_t>(Obj.getData().data()));
-    for (auto &Listener : EventListeners)
-      Listener->notifyObjectLoaded(Key, Obj, LoadedObjInfo);
-  }
-
-  void notifyFreed(orc::VModuleKey K, const object::ObjectFile &Obj) {
-    uint64_t Key = static_cast<uint64_t>(
-        reinterpret_cast<uintptr_t>(Obj.getData().data()));
-    for (auto &Listener : EventListeners)
-      Listener->notifyFreeingObject(Key);
-  }
-
-  orc::ExecutionSession ES;
-  std::unique_ptr<CompileCallbackMgr> CCMgr;
-
-  std::vector<JITEventListener *> EventListeners;
-
-  DataLayout DL;
-  SectionMemoryManager CCMgrMemMgr;
-
-  std::unique_ptr<orc::IndirectStubsManager> IndirectStubsMgr;
-
-  ObjLayerT ObjectLayer;
-  CompileLayerT CompileLayer;
-  std::unique_ptr<CODLayerT> CODLayer;
-
-  std::map<orc::VModuleKey, std::unique_ptr<detail::GenericLayer>> KeyLayers;
-
-  orc::LegacyLocalCXXRuntimeOverrides CXXRuntimeOverrides;
-  std::vector<orc::LegacyCtorDtorRunner<OrcCBindingsStack>> IRStaticDestructorRunners;
-  std::string ErrMsg;
-
-  ResolverMap Resolvers;
-};
-
-} // end namespace llvm
-
-#endif // LLVM_LIB_EXECUTIONENGINE_ORC_ORCCBINDINGSSTACK_H
diff --git a/llvm/lib/ExecutionEngine/Orc/OrcMCJITReplacement.cpp b/llvm/lib/ExecutionEngine/Orc/OrcMCJITReplacement.cpp
deleted file mode 100644
index 772a9c2c4ab2..000000000000
--- a/llvm/lib/ExecutionEngine/Orc/OrcMCJITReplacement.cpp
+++ /dev/null
@@ -1,138 +0,0 @@
-//===-------- OrcMCJITReplacement.cpp - Orc-based MCJIT replacement -------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#include "OrcMCJITReplacement.h"
-#include "llvm/ExecutionEngine/GenericValue.h"
-
-namespace {
-
-static struct RegisterJIT {
-  RegisterJIT() { llvm::orc::OrcMCJITReplacement::Register(); }
-} JITRegistrator;
-
-}
-
-extern "C" void LLVMLinkInOrcMCJITReplacement() {}
-
-namespace llvm {
-namespace orc {
-
-GenericValue
-OrcMCJITReplacement::runFunction(Function *F,
-                                 ArrayRef<GenericValue> ArgValues) {
-  assert(F && "Function *F was null at entry to run()");
-
-  void *FPtr = getPointerToFunction(F);
-  assert(FPtr && "Pointer to fn's code was null after getPointerToFunction");
-  FunctionType *FTy = F->getFunctionType();
-  Type *RetTy = FTy->getReturnType();
-
-  assert((FTy->getNumParams() == ArgValues.size() ||
-          (FTy->isVarArg() && FTy->getNumParams() <= ArgValues.size())) &&
-         "Wrong number of arguments passed into function!");
-  assert(FTy->getNumParams() == ArgValues.size() &&
-         "This doesn't support passing arguments through varargs (yet)!");
-
-  // Handle some common cases first.  These cases correspond to common `main'
-  // prototypes.
-  if (RetTy->isIntegerTy(32) || RetTy->isVoidTy()) {
-    switch (ArgValues.size()) {
-    case 3:
-      if (FTy->getParamType(0)->isIntegerTy(32) &&
-          FTy->getParamType(1)->isPointerTy() &&
-          FTy->getParamType(2)->isPointerTy()) {
-        int (*PF)(int, char **, const char **) =
-            (int (*)(int, char **, const char **))(intptr_t)FPtr;
-
-        // Call the function.
-        GenericValue rv;
-        rv.IntVal = APInt(32, PF(ArgValues[0].IntVal.getZExtValue(),
-                                 (char **)GVTOP(ArgValues[1]),
-                                 (const char **)GVTOP(ArgValues[2])));
-        return rv;
-      }
-      break;
-    case 2:
-      if (FTy->getParamType(0)->isIntegerTy(32) &&
-          FTy->getParamType(1)->isPointerTy()) {
-        int (*PF)(int, char **) = (int (*)(int, char **))(intptr_t)FPtr;
-
-        // Call the function.
-        GenericValue rv;
-        rv.IntVal = APInt(32, PF(ArgValues[0].IntVal.getZExtValue(),
-                                 (char **)GVTOP(ArgValues[1])));
-        return rv;
-      }
-      break;
-    case 1:
-      if (FTy->getNumParams() == 1 && FTy->getParamType(0)->isIntegerTy(32)) {
-        GenericValue rv;
-        int (*PF)(int) = (int (*)(int))(intptr_t)FPtr;
-        rv.IntVal = APInt(32, PF(ArgValues[0].IntVal.getZExtValue()));
-        return rv;
-      }
-      break;
-    }
-  }
-
-  // Handle cases where no arguments are passed first.
-  if (ArgValues.empty()) {
-    GenericValue rv;
-    switch (RetTy->getTypeID()) {
-    default:
-      llvm_unreachable("Unknown return type for function call!");
-    case Type::IntegerTyID: {
-      unsigned BitWidth = cast<IntegerType>(RetTy)->getBitWidth();
-      if (BitWidth == 1)
-        rv.IntVal = APInt(BitWidth, ((bool (*)())(intptr_t)FPtr)());
-      else if (BitWidth <= 8)
-        rv.IntVal = APInt(BitWidth, ((char (*)())(intptr_t)FPtr)());
-      else if (BitWidth <= 16)
-        rv.IntVal = APInt(BitWidth, ((short (*)())(intptr_t)FPtr)());
-      else if (BitWidth <= 32)
-        rv.IntVal = APInt(BitWidth, ((int (*)())(intptr_t)FPtr)());
-      else if (BitWidth <= 64)
-        rv.IntVal = APInt(BitWidth, ((int64_t (*)())(intptr_t)FPtr)());
-      else
-        llvm_unreachable("Integer types > 64 bits not supported");
-      return rv;
-    }
-    case Type::VoidTyID:
-      rv.IntVal = APInt(32, ((int (*)())(intptr_t)FPtr)());
-      return rv;
-    case Type::FloatTyID:
-      rv.FloatVal = ((float (*)())(intptr_t)FPtr)();
-      return rv;
-    case Type::DoubleTyID:
-      rv.DoubleVal = ((double (*)())(intptr_t)FPtr)();
-      return rv;
-    case Type::X86_FP80TyID:
-    case Type::FP128TyID:
-    case Type::PPC_FP128TyID:
-      llvm_unreachable("long double not supported yet");
-    case Type::PointerTyID:
-      return PTOGV(((void *(*)())(intptr_t)FPtr)());
-    }
-  }
-
-  llvm_unreachable("Full-featured argument passing not supported yet!");
-}
-
-void OrcMCJITReplacement::runStaticConstructorsDestructors(bool isDtors) {
-  auto &CtorDtorsMap = isDtors ? UnexecutedDestructors : UnexecutedConstructors;
-
-  for (auto &KV : CtorDtorsMap)
-    cantFail(LegacyCtorDtorRunner<LazyEmitLayerT>(
-                 AcknowledgeORCv1Deprecation, std::move(KV.second), KV.first)
-                 .runViaLayer(LazyEmitLayer));
-
-  CtorDtorsMap.clear();
-}
-
-} // End namespace orc.
-} // End namespace llvm.
diff --git a/llvm/lib/ExecutionEngine/Orc/OrcMCJITReplacement.h b/llvm/lib/ExecutionEngine/Orc/OrcMCJITReplacement.h
deleted file mode 100644
index 139572bd6977..000000000000
--- a/llvm/lib/ExecutionEngine/Orc/OrcMCJITReplacement.h
+++ /dev/null
@@ -1,502 +0,0 @@
-//===- OrcMCJITReplacement.h - Orc based MCJIT replacement ------*- C++ -*-===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-//
-// Orc based MCJIT replacement.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_LIB_EXECUTIONENGINE_ORC_ORCMCJITREPLACEMENT_H
-#define LLVM_LIB_EXECUTIONENGINE_ORC_ORCMCJITREPLACEMENT_H
-
-#include "llvm/ADT/ArrayRef.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/ADT/StringRef.h"
-#include "llvm/ExecutionEngine/ExecutionEngine.h"
-#include "llvm/ExecutionEngine/GenericValue.h"
-#include "llvm/ExecutionEngine/JITSymbol.h"
-#include "llvm/ExecutionEngine/Orc/CompileUtils.h"
-#include "llvm/ExecutionEngine/Orc/ExecutionUtils.h"
-#include "llvm/ExecutionEngine/Orc/IRCompileLayer.h"
-#include "llvm/ExecutionEngine/Orc/LazyEmittingLayer.h"
-#include "llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h"
-#include "llvm/ExecutionEngine/RTDyldMemoryManager.h"
-#include "llvm/ExecutionEngine/RuntimeDyld.h"
-#include "llvm/IR/DataLayout.h"
-#include "llvm/IR/Function.h"
-#include "llvm/IR/Mangler.h"
-#include "llvm/IR/Module.h"
-#include "llvm/Object/Archive.h"
-#include "llvm/Object/Binary.h"
-#include "llvm/Object/ObjectFile.h"
-#include "llvm/Support/Error.h"
-#include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/raw_ostream.h"
-#include "llvm/Target/TargetMachine.h"
-#include <algorithm>
-#include <cassert>
-#include <cstddef>
-#include <cstdint>
-#include <map>
-#include <memory>
-#include <set>
-#include <string>
-#include <vector>
-
-namespace llvm {
-
-class ObjectCache;
-
-namespace orc {
-
-class OrcMCJITReplacement : public ExecutionEngine {
-
-  // OrcMCJITReplacement needs to do a little extra book-keeping to ensure that
-  // Orc's automatic finalization doesn't kick in earlier than MCJIT clients are
-  // expecting - see finalizeMemory.
-  class MCJITReplacementMemMgr : public MCJITMemoryManager {
-  public:
-    MCJITReplacementMemMgr(OrcMCJITReplacement &M,
-                           std::shared_ptr<MCJITMemoryManager> ClientMM)
-      : M(M), ClientMM(std::move(ClientMM)) {}
-
-    uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
-                                 unsigned SectionID,
-                                 StringRef SectionName) override {
-      uint8_t *Addr =
-          ClientMM->allocateCodeSection(Size, Alignment, SectionID,
-                                        SectionName);
-      M.SectionsAllocatedSinceLastLoad.insert(Addr);
-      return Addr;
-    }
-
-    uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment,
-                                 unsigned SectionID, StringRef SectionName,
-                                 bool IsReadOnly) override {
-      uint8_t *Addr = ClientMM->allocateDataSection(Size, Alignment, SectionID,
-                                                    SectionName, IsReadOnly);
-      M.SectionsAllocatedSinceLastLoad.insert(Addr);
-      return Addr;
-    }
-
-    void reserveAllocationSpace(uintptr_t CodeSize, uint32_t CodeAlign,
-                                uintptr_t RODataSize, uint32_t RODataAlign,
-                                uintptr_t RWDataSize,
-                                uint32_t RWDataAlign) override {
-      return ClientMM->reserveAllocationSpace(CodeSize, CodeAlign,
-                                              RODataSize, RODataAlign,
-                                              RWDataSize, RWDataAlign);
-    }
-
-    bool needsToReserveAllocationSpace() override {
-      return ClientMM->needsToReserveAllocationSpace();
-    }
-
-    void registerEHFrames(uint8_t *Addr, uint64_t LoadAddr,
-                          size_t Size) override {
-      return ClientMM->registerEHFrames(Addr, LoadAddr, Size);
-    }
-
-    void deregisterEHFrames() override {
-      return ClientMM->deregisterEHFrames();
-    }
-
-    void notifyObjectLoaded(RuntimeDyld &RTDyld,
-                            const object::ObjectFile &O) override {
-      return ClientMM->notifyObjectLoaded(RTDyld, O);
-    }
-
-    void notifyObjectLoaded(ExecutionEngine *EE,
-                            const object::ObjectFile &O) override {
-      return ClientMM->notifyObjectLoaded(EE, O);
-    }
-
-    bool finalizeMemory(std::string *ErrMsg = nullptr) override {
-      // Each set of objects loaded will be finalized exactly once, but since
-      // symbol lookup during relocation may recursively trigger the
-      // loading/relocation of other modules, and since we're forwarding all
-      // finalizeMemory calls to a single underlying memory manager, we need to
-      // defer forwarding the call on until all necessary objects have been
-      // loaded. Otherwise, during the relocation of a leaf object, we will end
-      // up finalizing memory, causing a crash further up the stack when we
-      // attempt to apply relocations to finalized memory.
-      // To avoid finalizing too early, look at how many objects have been
-      // loaded but not yet finalized. This is a bit of a hack that relies on
-      // the fact that we're lazily emitting object files: The only way you can
-      // get more than one set of objects loaded but not yet finalized is if
-      // they were loaded during relocation of another set.
-      if (M.UnfinalizedSections.size() == 1)
-        return ClientMM->finalizeMemory(ErrMsg);
-      return false;
-    }
-
-  private:
-    OrcMCJITReplacement &M;
-    std::shared_ptr<MCJITMemoryManager> ClientMM;
-  };
-
-  class LinkingORCResolver : public orc::SymbolResolver {
-  public:
-    LinkingORCResolver(OrcMCJITReplacement &M) : M(M) {}
-
-    SymbolNameSet getResponsibilitySet(const SymbolNameSet &Symbols) override {
-      SymbolNameSet Result;
-
-      for (auto &S : Symbols) {
-        if (auto Sym = M.findMangledSymbol(*S)) {
-          if (!Sym.getFlags().isStrong())
-            Result.insert(S);
-        } else if (auto Err = Sym.takeError()) {
-          M.reportError(std::move(Err));
-          return SymbolNameSet();
-        } else {
-          if (auto Sym2 =
-                  M.ClientResolver->findSymbolInLogicalDylib(std::string(*S))) {
-            if (!Sym2.getFlags().isStrong())
-              Result.insert(S);
-          } else if (auto Err = Sym2.takeError()) {
-            M.reportError(std::move(Err));
-            return SymbolNameSet();
-          } else
-            Result.insert(S);
-        }
-      }
-
-      return Result;
-    }
-
-    SymbolNameSet lookup(std::shared_ptr<AsynchronousSymbolQuery> Query,
-                         SymbolNameSet Symbols) override {
-      SymbolNameSet UnresolvedSymbols;
-      bool NewSymbolsResolved = false;
-
-      for (auto &S : Symbols) {
-        if (auto Sym = M.findMangledSymbol(*S)) {
-          if (auto Addr = Sym.getAddress()) {
-            Query->notifySymbolMetRequiredState(
-                S, JITEvaluatedSymbol(*Addr, Sym.getFlags()));
-            NewSymbolsResolved = true;
-          } else {
-            M.ES.legacyFailQuery(*Query, Addr.takeError());
-            return SymbolNameSet();
-          }
-        } else if (auto Err = Sym.takeError()) {
-          M.ES.legacyFailQuery(*Query, std::move(Err));
-          return SymbolNameSet();
-        } else {
-          if (auto Sym2 = M.ClientResolver->findSymbol(std::string(*S))) {
-            if (auto Addr = Sym2.getAddress()) {
-              Query->notifySymbolMetRequiredState(
-                  S, JITEvaluatedSymbol(*Addr, Sym2.getFlags()));
-              NewSymbolsResolved = true;
-            } else {
-              M.ES.legacyFailQuery(*Query, Addr.takeError());
-              return SymbolNameSet();
-            }
-          } else if (auto Err = Sym2.takeError()) {
-            M.ES.legacyFailQuery(*Query, std::move(Err));
-            return SymbolNameSet();
-          } else
-            UnresolvedSymbols.insert(S);
-        }
-      }
-
-      if (NewSymbolsResolved && Query->isComplete())
-        Query->handleComplete();
-
-      return UnresolvedSymbols;
-    }
-
-  private:
-    OrcMCJITReplacement &M;
-  };
-
-private:
-  static ExecutionEngine *
-  createOrcMCJITReplacement(std::string *ErrorMsg,
-                            std::shared_ptr<MCJITMemoryManager> MemMgr,
-                            std::shared_ptr<LegacyJITSymbolResolver> Resolver,
-                            std::unique_ptr<TargetMachine> TM) {
-    return new OrcMCJITReplacement(std::move(MemMgr), std::move(Resolver),
-                                   std::move(TM));
-  }
-
-  void reportError(Error Err) {
-    logAllUnhandledErrors(std::move(Err), errs(), "MCJIT error: ");
-  }
-
-public:
-  OrcMCJITReplacement(std::shared_ptr<MCJITMemoryManager> MemMgr,
-                      std::shared_ptr<LegacyJITSymbolResolver> ClientResolver,
-                      std::unique_ptr<TargetMachine> TM)
-      : ExecutionEngine(TM->createDataLayout()), TM(std::move(TM)),
-        MemMgr(
-            std::make_shared<MCJITReplacementMemMgr>(*this, std::move(MemMgr))),
-        Resolver(std::make_shared<LinkingORCResolver>(*this)),
-        ClientResolver(std::move(ClientResolver)), NotifyObjectLoaded(*this),
-        NotifyFinalized(*this),
-        ObjectLayer(
-            AcknowledgeORCv1Deprecation, ES,
-            [this](VModuleKey K) {
-              return ObjectLayerT::Resources{this->MemMgr, this->Resolver};
-            },
-            NotifyObjectLoaded, NotifyFinalized),
-        CompileLayer(AcknowledgeORCv1Deprecation, ObjectLayer,
-                     SimpleCompiler(*this->TM),
-                     [this](VModuleKey K, std::unique_ptr<Module> M) {
-                       Modules.push_back(std::move(M));
-                     }),
-        LazyEmitLayer(AcknowledgeORCv1Deprecation, CompileLayer) {}
-
-  static void Register() {
-    OrcMCJITReplacementCtor = createOrcMCJITReplacement;
-  }
-
-  void addModule(std::unique_ptr<Module> M) override {
-    // If this module doesn't have a DataLayout attached then attach the
-    // default.
-    if (M->getDataLayout().isDefault()) {
-      M->setDataLayout(getDataLayout());
-    } else {
-      assert(M->getDataLayout() == getDataLayout() && "DataLayout Mismatch");
-    }
-
-    // Rename, bump linkage and record static constructors and destructors.
-    // We have to do this before we hand over ownership of the module to the
-    // JIT.
-    std::vector<std::string> CtorNames, DtorNames;
-    {
-      unsigned CtorId = 0, DtorId = 0;
-      for (auto Ctor : orc::getConstructors(*M)) {
-        std::string NewCtorName = ("__ORCstatic_ctor." + Twine(CtorId++)).str();
-        Ctor.Func->setName(NewCtorName);
-        Ctor.Func->setLinkage(GlobalValue::ExternalLinkage);
-        Ctor.Func->setVisibility(GlobalValue::HiddenVisibility);
-        CtorNames.push_back(mangle(NewCtorName));
-      }
-      for (auto Dtor : orc::getDestructors(*M)) {
-        std::string NewDtorName = ("__ORCstatic_dtor." + Twine(DtorId++)).str();
-        dbgs() << "Found dtor: " << NewDtorName << "\n";
-        Dtor.Func->setName(NewDtorName);
-        Dtor.Func->setLinkage(GlobalValue::ExternalLinkage);
-        Dtor.Func->setVisibility(GlobalValue::HiddenVisibility);
-        DtorNames.push_back(mangle(NewDtorName));
-      }
-    }
-
-    auto K = ES.allocateVModule();
-
-    UnexecutedConstructors[K] = std::move(CtorNames);
-    UnexecutedDestructors[K] = std::move(DtorNames);
-
-    cantFail(LazyEmitLayer.addModule(K, std::move(M)));
-  }
-
-  void addObjectFile(std::unique_ptr<object::ObjectFile> O) override {
-    cantFail(ObjectLayer.addObject(
-        ES.allocateVModule(), MemoryBuffer::getMemBufferCopy(O->getData())));
-  }
-
-  void addObjectFile(object::OwningBinary<object::ObjectFile> O) override {
-    std::unique_ptr<object::ObjectFile> Obj;
-    std::unique_ptr<MemoryBuffer> ObjBuffer;
-    std::tie(Obj, ObjBuffer) = O.takeBinary();
-    cantFail(ObjectLayer.addObject(ES.allocateVModule(), std::move(ObjBuffer)));
-  }
-
-  void addArchive(object::OwningBinary<object::Archive> A) override {
-    Archives.push_back(std::move(A));
-  }
-
-  bool removeModule(Module *M) override {
-    auto I = Modules.begin();
-    for (auto E = Modules.end(); I != E; ++I)
-      if (I->get() == M)
-        break;
-    if (I == Modules.end())
-      return false;
-    Modules.erase(I);
-    return true;
-  }
-
-  uint64_t getSymbolAddress(StringRef Name) {
-    return cantFail(findSymbol(Name).getAddress());
-  }
-
-  JITSymbol findSymbol(StringRef Name) {
-    return findMangledSymbol(mangle(Name));
-  }
-
-  void finalizeObject() override {
-    // This is deprecated - Aim to remove in ExecutionEngine.
-    // REMOVE IF POSSIBLE - Doesn't make sense for New JIT.
-  }
-
-  void mapSectionAddress(const void *LocalAddress,
-                         uint64_t TargetAddress) override {
-    for (auto &P : UnfinalizedSections)
-      if (P.second.count(LocalAddress))
-        ObjectLayer.mapSectionAddress(P.first, LocalAddress, TargetAddress);
-  }
-
-  uint64_t getGlobalValueAddress(const std::string &Name) override {
-    return getSymbolAddress(Name);
-  }
-
-  uint64_t getFunctionAddress(const std::string &Name) override {
-    return getSymbolAddress(Name);
-  }
-
-  void *getPointerToFunction(Function *F) override {
-    uint64_t FAddr = getSymbolAddress(F->getName());
-    return reinterpret_cast<void *>(static_cast<uintptr_t>(FAddr));
-  }
-
-  void *getPointerToNamedFunction(StringRef Name,
-                                  bool AbortOnFailure = true) override {
-    uint64_t Addr = getSymbolAddress(Name);
-    if (!Addr && AbortOnFailure)
-      llvm_unreachable("Missing symbol!");
-    return reinterpret_cast<void *>(static_cast<uintptr_t>(Addr));
-  }
-
-  GenericValue runFunction(Function *F,
-                           ArrayRef<GenericValue> ArgValues) override;
-
-  void setObjectCache(ObjectCache *NewCache) override {
-    CompileLayer.getCompiler().setObjectCache(NewCache);
-  }
-
-  void setProcessAllSections(bool ProcessAllSections) override {
-    ObjectLayer.setProcessAllSections(ProcessAllSections);
-  }
-
-  void runStaticConstructorsDestructors(bool isDtors) override;
-
-private:
-  JITSymbol findMangledSymbol(StringRef Name) {
-    if (auto Sym = LazyEmitLayer.findSymbol(std::string(Name), false))
-      return Sym;
-    if (auto Sym = ClientResolver->findSymbol(std::string(Name)))
-      return Sym;
-    if (auto Sym = scanArchives(Name))
-      return Sym;
-
-    return nullptr;
-  }
-
-  JITSymbol scanArchives(StringRef Name) {
-    for (object::OwningBinary<object::Archive> &OB : Archives) {
-      object::Archive *A = OB.getBinary();
-      // Look for our symbols in each Archive
-      auto OptionalChildOrErr = A->findSym(Name);
-      if (!OptionalChildOrErr)
-        report_fatal_error(OptionalChildOrErr.takeError());
-      auto &OptionalChild = *OptionalChildOrErr;
-      if (OptionalChild) {
-        // FIXME: Support nested archives?
-        Expected<std::unique_ptr<object::Binary>> ChildBinOrErr =
-            OptionalChild->getAsBinary();
-        if (!ChildBinOrErr) {
-          // TODO: Actually report errors helpfully.
-          consumeError(ChildBinOrErr.takeError());
-          continue;
-        }
-        std::unique_ptr<object::Binary> &ChildBin = ChildBinOrErr.get();
-        if (ChildBin->isObject()) {
-          cantFail(ObjectLayer.addObject(
-              ES.allocateVModule(),
-              MemoryBuffer::getMemBufferCopy(ChildBin->getData())));
-          if (auto Sym = ObjectLayer.findSymbol(Name, true))
-            return Sym;
-        }
-      }
-    }
-    return nullptr;
-  }
-
-  class NotifyObjectLoadedT {
-  public:
-    using LoadedObjInfoListT =
-        std::vector<std::unique_ptr<RuntimeDyld::LoadedObjectInfo>>;
-
-    NotifyObjectLoadedT(OrcMCJITReplacement &M) : M(M) {}
-
-    void operator()(VModuleKey K, const object::ObjectFile &Obj,
-                    const RuntimeDyld::LoadedObjectInfo &Info) const {
-      M.UnfinalizedSections[K] = std::move(M.SectionsAllocatedSinceLastLoad);
-      M.SectionsAllocatedSinceLastLoad = SectionAddrSet();
-      M.MemMgr->notifyObjectLoaded(&M, Obj);
-    }
-  private:
-    OrcMCJITReplacement &M;
-  };
-
-  class NotifyFinalizedT {
-  public:
-    NotifyFinalizedT(OrcMCJITReplacement &M) : M(M) {}
-
-    void operator()(VModuleKey K, const object::ObjectFile &Obj,
-                    const RuntimeDyld::LoadedObjectInfo &Info) {
-      M.UnfinalizedSections.erase(K);
-    }
-
-  private:
-    OrcMCJITReplacement &M;
-  };
-
-  std::string mangle(StringRef Name) {
-    std::string MangledName;
-    {
-      raw_string_ostream MangledNameStream(MangledName);
-      Mang.getNameWithPrefix(MangledNameStream, Name, getDataLayout());
-    }
-    return MangledName;
-  }
-
-  using ObjectLayerT = LegacyRTDyldObjectLinkingLayer;
-  using CompileLayerT = LegacyIRCompileLayer<ObjectLayerT, orc::SimpleCompiler>;
-  using LazyEmitLayerT = LazyEmittingLayer<CompileLayerT>;
-
-  ExecutionSession ES;
-
-  std::unique_ptr<TargetMachine> TM;
-  std::shared_ptr<MCJITReplacementMemMgr> MemMgr;
-  std::shared_ptr<LinkingORCResolver> Resolver;
-  std::shared_ptr<LegacyJITSymbolResolver> ClientResolver;
-  Mangler Mang;
-
-  // IMPORTANT: ShouldDelete *must* come before LocalModules: The shared_ptr
-  // delete blocks in LocalModules refer to the ShouldDelete map, so
-  // LocalModules needs to be destructed before ShouldDelete.
-  std::map<Module*, bool> ShouldDelete;
-
-  NotifyObjectLoadedT NotifyObjectLoaded;
-  NotifyFinalizedT NotifyFinalized;
-
-  ObjectLayerT ObjectLayer;
-  CompileLayerT CompileLayer;
-  LazyEmitLayerT LazyEmitLayer;
-
-  std::map<VModuleKey, std::vector<std::string>> UnexecutedConstructors;
-  std::map<VModuleKey, std::vector<std::string>> UnexecutedDestructors;
-
-  // We need to store ObjLayerT::ObjSetHandles for each of the object sets
-  // that have been emitted but not yet finalized so that we can forward the
-  // mapSectionAddress calls appropriately.
-  using SectionAddrSet = std::set<const void *>;
-  SectionAddrSet SectionsAllocatedSinceLastLoad;
-  std::map<VModuleKey, SectionAddrSet> UnfinalizedSections;
-
-  std::vector<object::OwningBinary<object::Archive>> Archives;
-};
-
-} // end namespace orc
-
-} // end namespace llvm
-
-#endif // LLVM_LIB_EXECUTIONENGINE_ORC_MCJITREPLACEMENT_H
diff --git a/llvm/lib/ExecutionEngine/Orc/OrcV2CBindings.cpp b/llvm/lib/ExecutionEngine/Orc/OrcV2CBindings.cpp
index 5933c2e666d1..dfdd2c6c669f 100644
--- a/llvm/lib/ExecutionEngine/Orc/OrcV2CBindings.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/OrcV2CBindings.cpp
@@ -6,11 +6,15 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm-c/LLJIT.h"
 #include "llvm-c/Orc.h"
+#include "llvm-c/OrcEE.h"
 #include "llvm-c/TargetMachine.h"
 
 #include "llvm/ExecutionEngine/Orc/JITTargetMachineBuilder.h"
 #include "llvm/ExecutionEngine/Orc/LLJIT.h"
+#include "llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h"
+#include "llvm/ExecutionEngine/SectionMemoryManager.h"
 
 using namespace llvm;
 using namespace llvm::orc;
@@ -18,6 +22,8 @@ using namespace llvm::orc;
 namespace llvm {
 namespace orc {
 
+class InProgressLookupState;
+
 class OrcV2CAPIHelper {
 public:
   using PoolEntry = SymbolStringPtr::PoolEntry;
@@ -29,58 +35,278 @@ public:
     return Result;
   }
 
+  static SymbolStringPtr retainSymbolStringPtr(PoolEntryPtr P) {
+    return SymbolStringPtr(P);
+  }
+
   static PoolEntryPtr getRawPoolEntryPtr(const SymbolStringPtr &S) {
     return S.S;
   }
 
+  static void retainPoolEntry(PoolEntryPtr P) {
+    SymbolStringPtr S(P);
+    S.S = nullptr;
+  }
+
   static void releasePoolEntry(PoolEntryPtr P) {
     SymbolStringPtr S;
     S.S = P;
   }
+
+  static InProgressLookupState *extractLookupState(LookupState &LS) {
+    return LS.IPLS.release();
+  }
+
+  static void resetLookupState(LookupState &LS, InProgressLookupState *IPLS) {
+    return LS.reset(IPLS);
+  }
 };
 
-} // end namespace orc
-} // end namespace llvm
+} // namespace orc
+} // namespace llvm
 
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(ExecutionSession, LLVMOrcExecutionSessionRef)
+DEFINE_SIMPLE_CONVERSION_FUNCTIONS(SymbolStringPool, LLVMOrcSymbolStringPoolRef)
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(OrcV2CAPIHelper::PoolEntry,
                                    LLVMOrcSymbolStringPoolEntryRef)
+DEFINE_SIMPLE_CONVERSION_FUNCTIONS(MaterializationUnit,
+                                   LLVMOrcMaterializationUnitRef)
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(JITDylib, LLVMOrcJITDylibRef)
-DEFINE_SIMPLE_CONVERSION_FUNCTIONS(JITDylib::DefinitionGenerator,
-                                   LLVMOrcJITDylibDefinitionGeneratorRef)
+DEFINE_SIMPLE_CONVERSION_FUNCTIONS(ResourceTracker, LLVMOrcResourceTrackerRef)
+DEFINE_SIMPLE_CONVERSION_FUNCTIONS(DefinitionGenerator,
+                                   LLVMOrcDefinitionGeneratorRef)
+DEFINE_SIMPLE_CONVERSION_FUNCTIONS(InProgressLookupState, LLVMOrcLookupStateRef)
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(ThreadSafeContext,
                                    LLVMOrcThreadSafeContextRef)
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(ThreadSafeModule, LLVMOrcThreadSafeModuleRef)
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(JITTargetMachineBuilder,
                                    LLVMOrcJITTargetMachineBuilderRef)
+DEFINE_SIMPLE_CONVERSION_FUNCTIONS(ObjectLayer, LLVMOrcObjectLayerRef)
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(LLJITBuilder, LLVMOrcLLJITBuilderRef)
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(LLJIT, LLVMOrcLLJITRef)
 
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(TargetMachine, LLVMTargetMachineRef)
 
+namespace llvm {
+namespace orc {
+
+class CAPIDefinitionGenerator final : public DefinitionGenerator {
+public:
+  CAPIDefinitionGenerator(
+      void *Ctx,
+      LLVMOrcCAPIDefinitionGeneratorTryToGenerateFunction TryToGenerate)
+      : Ctx(Ctx), TryToGenerate(TryToGenerate) {}
+
+  Error tryToGenerate(LookupState &LS, LookupKind K, JITDylib &JD,
+                      JITDylibLookupFlags JDLookupFlags,
+                      const SymbolLookupSet &LookupSet) override {
+
+    // Take the lookup state.
+    LLVMOrcLookupStateRef LSR = ::wrap(OrcV2CAPIHelper::extractLookupState(LS));
+
+    // Translate the lookup kind.
+    LLVMOrcLookupKind CLookupKind;
+    switch (K) {
+    case LookupKind::Static:
+      CLookupKind = LLVMOrcLookupKindStatic;
+      break;
+    case LookupKind::DLSym:
+      CLookupKind = LLVMOrcLookupKindDLSym;
+      break;
+    }
+
+    // Translate the JITDylibSearchFlags.
+    LLVMOrcJITDylibLookupFlags CJDLookupFlags;
+    switch (JDLookupFlags) {
+    case JITDylibLookupFlags::MatchExportedSymbolsOnly:
+      CJDLookupFlags = LLVMOrcJITDylibLookupFlagsMatchExportedSymbolsOnly;
+      break;
+    case JITDylibLookupFlags::MatchAllSymbols:
+      CJDLookupFlags = LLVMOrcJITDylibLookupFlagsMatchAllSymbols;
+      break;
+    }
+
+    // Translate the lookup set.
+    std::vector<LLVMOrcCLookupSetElement> CLookupSet;
+    CLookupSet.reserve(LookupSet.size());
+    for (auto &KV : LookupSet) {
+      LLVMOrcSymbolLookupFlags SLF;
+      LLVMOrcSymbolStringPoolEntryRef Name =
+        ::wrap(OrcV2CAPIHelper::getRawPoolEntryPtr(KV.first));
+      switch (KV.second) {
+      case SymbolLookupFlags::RequiredSymbol:
+        SLF = LLVMOrcSymbolLookupFlagsRequiredSymbol;
+        break;
+      case SymbolLookupFlags::WeaklyReferencedSymbol:
+        SLF = LLVMOrcSymbolLookupFlagsWeaklyReferencedSymbol;
+        break;
+      }
+      CLookupSet.push_back({Name, SLF});
+    }
+
+    // Run the C TryToGenerate function.
+    auto Err = unwrap(TryToGenerate(::wrap(this), Ctx, &LSR, CLookupKind,
+                                    ::wrap(&JD), CJDLookupFlags,
+                                    CLookupSet.data(), CLookupSet.size()));
+
+    // Restore the lookup state.
+    OrcV2CAPIHelper::resetLookupState(LS, ::unwrap(LSR));
+
+    return Err;
+  }
+
+private:
+  void *Ctx;
+  LLVMOrcCAPIDefinitionGeneratorTryToGenerateFunction TryToGenerate;
+};
+
+} // end namespace orc
+} // end namespace llvm
+
+void LLVMOrcExecutionSessionSetErrorReporter(
+    LLVMOrcExecutionSessionRef ES, LLVMOrcErrorReporterFunction ReportError,
+    void *Ctx) {
+  unwrap(ES)->setErrorReporter(
+      [=](Error Err) { ReportError(Ctx, wrap(std::move(Err))); });
+}
+
+LLVMOrcSymbolStringPoolRef
+LLVMOrcExecutionSessionGetSymbolStringPool(LLVMOrcExecutionSessionRef ES) {
+  return wrap(unwrap(ES)->getSymbolStringPool().get());
+}
+
+void LLVMOrcSymbolStringPoolClearDeadEntries(LLVMOrcSymbolStringPoolRef SSP) {
+  unwrap(SSP)->clearDeadEntries();
+}
+
 LLVMOrcSymbolStringPoolEntryRef
 LLVMOrcExecutionSessionIntern(LLVMOrcExecutionSessionRef ES, const char *Name) {
   return wrap(
       OrcV2CAPIHelper::releaseSymbolStringPtr(unwrap(ES)->intern(Name)));
 }
 
+void LLVMOrcRetainSymbolStringPoolEntry(LLVMOrcSymbolStringPoolEntryRef S) {
+  OrcV2CAPIHelper::retainPoolEntry(unwrap(S));
+}
+
 void LLVMOrcReleaseSymbolStringPoolEntry(LLVMOrcSymbolStringPoolEntryRef S) {
   OrcV2CAPIHelper::releasePoolEntry(unwrap(S));
 }
 
-void LLVMOrcDisposeJITDylibDefinitionGenerator(
-    LLVMOrcJITDylibDefinitionGeneratorRef DG) {
-  delete unwrap(DG);
+const char *LLVMOrcSymbolStringPoolEntryStr(LLVMOrcSymbolStringPoolEntryRef S) {
+  return unwrap(S)->getKey().data();
+}
+
+LLVMOrcResourceTrackerRef
+LLVMOrcJITDylibCreateResourceTracker(LLVMOrcJITDylibRef JD) {
+  auto RT = unwrap(JD)->createResourceTracker();
+  // Retain the pointer for the C API client.
+  RT->Retain();
+  return wrap(RT.get());
+}
+
+LLVMOrcResourceTrackerRef
+LLVMOrcJITDylibGetDefaultResourceTracker(LLVMOrcJITDylibRef JD) {
+  auto RT = unwrap(JD)->getDefaultResourceTracker();
+  // Retain the pointer for the C API client.
+  return wrap(RT.get());
+}
+
+void LLVMOrcReleaseResourceTracker(LLVMOrcResourceTrackerRef RT) {
+  ResourceTrackerSP TmpRT(unwrap(RT));
+  TmpRT->Release();
+}
+
+void LLVMOrcResourceTrackerTransferTo(LLVMOrcResourceTrackerRef SrcRT,
+                                      LLVMOrcResourceTrackerRef DstRT) {
+  ResourceTrackerSP TmpRT(unwrap(SrcRT));
+  TmpRT->transferTo(*unwrap(DstRT));
+}
+
+LLVMErrorRef LLVMOrcResourceTrackerRemove(LLVMOrcResourceTrackerRef RT) {
+  ResourceTrackerSP TmpRT(unwrap(RT));
+  return wrap(TmpRT->remove());
+}
+
+void LLVMOrcDisposeDefinitionGenerator(LLVMOrcDefinitionGeneratorRef DG) {
+  std::unique_ptr<DefinitionGenerator> TmpDG(unwrap(DG));
+}
+
+void LLVMOrcDisposeMaterializationUnit(LLVMOrcMaterializationUnitRef MU) {
+  std::unique_ptr<MaterializationUnit> TmpMU(unwrap(MU));
+}
+
+LLVMOrcMaterializationUnitRef
+LLVMOrcAbsoluteSymbols(LLVMOrcCSymbolMapPairs Syms, size_t NumPairs) {
+  SymbolMap SM;
+  for (size_t I = 0; I != NumPairs; ++I) {
+    JITSymbolFlags Flags;
+
+    if (Syms[I].Sym.Flags.GenericFlags & LLVMJITSymbolGenericFlagsExported)
+      Flags |= JITSymbolFlags::Exported;
+    if (Syms[I].Sym.Flags.GenericFlags & LLVMJITSymbolGenericFlagsWeak)
+      Flags |= JITSymbolFlags::Weak;
+
+    Flags.getTargetFlags() = Syms[I].Sym.Flags.TargetFlags;
+
+    SM[OrcV2CAPIHelper::retainSymbolStringPtr(unwrap(Syms[I].Name))] =
+        JITEvaluatedSymbol(Syms[I].Sym.Address, Flags);
+  }
+
+  return wrap(absoluteSymbols(std::move(SM)).release());
+}
+
+LLVMOrcJITDylibRef
+LLVMOrcExecutionSessionCreateBareJITDylib(LLVMOrcExecutionSessionRef ES,
+                                          const char *Name) {
+  return wrap(&unwrap(ES)->createBareJITDylib(Name));
+}
+
+LLVMErrorRef
+LLVMOrcExecutionSessionCreateJITDylib(LLVMOrcExecutionSessionRef ES,
+                                      LLVMOrcJITDylibRef *Result,
+                                      const char *Name) {
+  auto JD = unwrap(ES)->createJITDylib(Name);
+  if (!JD)
+    return wrap(JD.takeError());
+  *Result = wrap(&*JD);
+  return LLVMErrorSuccess;
+}
+
+LLVMOrcJITDylibRef
+LLVMOrcExecutionSessionGetJITDylibByName(LLVMOrcExecutionSessionRef ES,
+                                         const char *Name) {
+  return wrap(unwrap(ES)->getJITDylibByName(Name));
+}
+
+LLVMErrorRef LLVMOrcJITDylibDefine(LLVMOrcJITDylibRef JD,
+                                   LLVMOrcMaterializationUnitRef MU) {
+  std::unique_ptr<MaterializationUnit> TmpMU(unwrap(MU));
+
+  if (auto Err = unwrap(JD)->define(TmpMU)) {
+    TmpMU.release();
+    return wrap(std::move(Err));
+  }
+  return LLVMErrorSuccess;
+}
+
+LLVMErrorRef LLVMOrcJITDylibClear(LLVMOrcJITDylibRef JD) {
+  return wrap(unwrap(JD)->clear());
 }
 
 void LLVMOrcJITDylibAddGenerator(LLVMOrcJITDylibRef JD,
-                                 LLVMOrcJITDylibDefinitionGeneratorRef DG) {
-  unwrap(JD)->addGenerator(
-      std::unique_ptr<JITDylib::DefinitionGenerator>(unwrap(DG)));
+                                 LLVMOrcDefinitionGeneratorRef DG) {
+  unwrap(JD)->addGenerator(std::unique_ptr<DefinitionGenerator>(unwrap(DG)));
+}
+
+LLVMOrcDefinitionGeneratorRef LLVMOrcCreateCustomCAPIDefinitionGenerator(
+    LLVMOrcCAPIDefinitionGeneratorTryToGenerateFunction F, void *Ctx) {
+  auto DG = std::make_unique<CAPIDefinitionGenerator>(Ctx, F);
+  return wrap(DG.release());
 }
 
 LLVMErrorRef LLVMOrcCreateDynamicLibrarySearchGeneratorForProcess(
-    LLVMOrcJITDylibDefinitionGeneratorRef *Result, char GlobalPrefix,
+    LLVMOrcDefinitionGeneratorRef *Result, char GlobalPrefix,
     LLVMOrcSymbolPredicate Filter, void *FilterCtx) {
   assert(Result && "Result can not be null");
   assert((Filter || !FilterCtx) &&
@@ -89,7 +315,7 @@ LLVMErrorRef LLVMOrcCreateDynamicLibrarySearchGeneratorForProcess(
   DynamicLibrarySearchGenerator::SymbolPredicate Pred;
   if (Filter)
     Pred = [=](const SymbolStringPtr &Name) -> bool {
-      return Filter(wrap(OrcV2CAPIHelper::getRawPoolEntryPtr(Name)), FilterCtx);
+      return Filter(FilterCtx, wrap(OrcV2CAPIHelper::getRawPoolEntryPtr(Name)));
     };
 
   auto ProcessSymsGenerator =
@@ -143,7 +369,7 @@ LLVMErrorRef LLVMOrcJITTargetMachineBuilderDetectHost(
 }
 
 LLVMOrcJITTargetMachineBuilderRef
-LLVMOrcJITTargetMachineBuilderFromTargetMachine(LLVMTargetMachineRef TM) {
+LLVMOrcJITTargetMachineBuilderCreateFromTargetMachine(LLVMTargetMachineRef TM) {
   auto *TemplateTM = unwrap(TM);
 
   auto JTMB =
@@ -167,6 +393,10 @@ void LLVMOrcDisposeJITTargetMachineBuilder(
   delete unwrap(JTMB);
 }
 
+void lLVMOrcDisposeObjectLayer(LLVMOrcObjectLayerRef ObjLayer) {
+  delete unwrap(ObjLayer);
+}
+
 LLVMOrcLLJITBuilderRef LLVMOrcCreateLLJITBuilder(void) {
   return wrap(new LLJITBuilder());
 }
@@ -180,6 +410,17 @@ void LLVMOrcLLJITBuilderSetJITTargetMachineBuilder(
   unwrap(Builder)->setJITTargetMachineBuilder(*unwrap(JTMB));
 }
 
+void LLVMOrcLLJITBuilderSetObjectLinkingLayerCreator(
+    LLVMOrcLLJITBuilderRef Builder,
+    LLVMOrcLLJITBuilderObjectLinkingLayerCreatorFunction F, void *Ctx) {
+  unwrap(Builder)->setObjectLinkingLayerCreator(
+      [=](ExecutionSession &ES, const Triple &TT) {
+        auto TTStr = TT.str();
+        return std::unique_ptr<ObjectLayer>(
+            unwrap(F(Ctx, wrap(&ES), TTStr.c_str())));
+      });
+}
+
 LLVMErrorRef LLVMOrcCreateLLJIT(LLVMOrcLLJITRef *Result,
                                 LLVMOrcLLJITBuilderRef Builder) {
   assert(Result && "Result can not be null");
@@ -232,10 +473,27 @@ LLVMErrorRef LLVMOrcLLJITAddObjectFile(LLVMOrcLLJITRef J, LLVMOrcJITDylibRef JD,
       *unwrap(JD), std::unique_ptr<MemoryBuffer>(unwrap(ObjBuffer))));
 }
 
+LLVMErrorRef LLVMOrcLLJITAddObjectFileWithRT(LLVMOrcLLJITRef J,
+                                             LLVMOrcResourceTrackerRef RT,
+                                             LLVMMemoryBufferRef ObjBuffer) {
+  return wrap(unwrap(J)->addObjectFile(
+      ResourceTrackerSP(unwrap(RT)),
+      std::unique_ptr<MemoryBuffer>(unwrap(ObjBuffer))));
+}
+
 LLVMErrorRef LLVMOrcLLJITAddLLVMIRModule(LLVMOrcLLJITRef J,
                                          LLVMOrcJITDylibRef JD,
                                          LLVMOrcThreadSafeModuleRef TSM) {
-  return wrap(unwrap(J)->addIRModule(*unwrap(JD), std::move(*unwrap(TSM))));
+  std::unique_ptr<ThreadSafeModule> TmpTSM(unwrap(TSM));
+  return wrap(unwrap(J)->addIRModule(*unwrap(JD), std::move(*TmpTSM)));
+}
+
+LLVMErrorRef LLVMOrcLLJITAddLLVMIRModuleWithRT(LLVMOrcLLJITRef J,
+                                               LLVMOrcResourceTrackerRef RT,
+                                               LLVMOrcThreadSafeModuleRef TSM) {
+  std::unique_ptr<ThreadSafeModule> TmpTSM(unwrap(TSM));
+  return wrap(unwrap(J)->addIRModule(ResourceTrackerSP(unwrap(RT)),
+                                     std::move(*TmpTSM)));
 }
 
 LLVMErrorRef LLVMOrcLLJITLookup(LLVMOrcLLJITRef J,
@@ -252,3 +510,20 @@ LLVMErrorRef LLVMOrcLLJITLookup(LLVMOrcLLJITRef J,
   *Result = Sym->getAddress();
   return LLVMErrorSuccess;
 }
+
+LLVMOrcObjectLayerRef
+LLVMOrcCreateRTDyldObjectLinkingLayerWithSectionMemoryManager(
+    LLVMOrcExecutionSessionRef ES) {
+  assert(ES && "ES must not be null");
+  return wrap(new RTDyldObjectLinkingLayer(
+      *unwrap(ES), [] { return std::make_unique<SectionMemoryManager>(); }));
+}
+
+void LLVMOrcRTDyldObjectLinkingLayerRegisterJITEventListener(
+    LLVMOrcObjectLayerRef RTDyldObjLinkingLayer,
+    LLVMJITEventListenerRef Listener) {
+  assert(RTDyldObjLinkingLayer && "RTDyldObjLinkingLayer must not be null");
+  assert(Listener && "Listener must not be null");
+  reinterpret_cast<RTDyldObjectLinkingLayer *>(unwrap(RTDyldObjLinkingLayer))
+      ->registerJITEventListener(*unwrap(Listener));
+}
diff --git a/llvm/lib/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.cpp b/llvm/lib/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.cpp
index 21925726072e..0ad666ebbebd 100644
--- a/llvm/lib/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.cpp
@@ -18,7 +18,7 @@ class JITDylibSearchOrderResolver : public JITSymbolResolver {
 public:
   JITDylibSearchOrderResolver(MaterializationResponsibility &MR) : MR(MR) {}
 
-  void lookup(const LookupSet &Symbols, OnResolvedFunction OnResolved) {
+  void lookup(const LookupSet &Symbols, OnResolvedFunction OnResolved) override {
     auto &ES = MR.getTargetJITDylib().getExecutionSession();
     SymbolLookupSet InternedSymbols;
 
@@ -55,7 +55,7 @@ public:
               RegisterDependencies);
   }
 
-  Expected<LookupSet> getResponsibilitySet(const LookupSet &Symbols) {
+  Expected<LookupSet> getResponsibilitySet(const LookupSet &Symbols) override {
     LookupSet Result;
 
     for (auto &KV : MR.getSymbols()) {
@@ -77,35 +77,26 @@ namespace orc {
 
 RTDyldObjectLinkingLayer::RTDyldObjectLinkingLayer(
     ExecutionSession &ES, GetMemoryManagerFunction GetMemoryManager)
-    : ObjectLayer(ES), GetMemoryManager(GetMemoryManager) {}
+    : ObjectLayer(ES), GetMemoryManager(GetMemoryManager) {
+  ES.registerResourceManager(*this);
+}
 
 RTDyldObjectLinkingLayer::~RTDyldObjectLinkingLayer() {
-  std::lock_guard<std::mutex> Lock(RTDyldLayerMutex);
-  for (auto &MemMgr : MemMgrs) {
-    for (auto *L : EventListeners)
-      L->notifyFreeingObject(
-          static_cast<uint64_t>(reinterpret_cast<uintptr_t>(MemMgr.get())));
-    MemMgr->deregisterEHFrames();
-  }
+  assert(MemMgrs.empty() && "Layer destroyed with resources still attached");
 }
 
-void RTDyldObjectLinkingLayer::emit(MaterializationResponsibility R,
-                                    std::unique_ptr<MemoryBuffer> O) {
+void RTDyldObjectLinkingLayer::emit(
+    std::unique_ptr<MaterializationResponsibility> R,
+    std::unique_ptr<MemoryBuffer> O) {
   assert(O && "Object must not be null");
 
-  // This method launches an asynchronous link step that will fulfill our
-  // materialization responsibility. We need to switch R to be heap
-  // allocated before that happens so it can live as long as the asynchronous
-  // link needs it to (i.e. it must be able to outlive this method).
-  auto SharedR = std::make_shared<MaterializationResponsibility>(std::move(R));
-
   auto &ES = getExecutionSession();
 
   auto Obj = object::ObjectFile::createObjectFile(*O);
 
   if (!Obj) {
     getExecutionSession().reportError(Obj.takeError());
-    SharedR->failMaterialization();
+    R->failMaterialization();
     return;
   }
 
@@ -121,7 +112,7 @@ void RTDyldObjectLinkingLayer::emit(MaterializationResponsibility R,
           continue;
       } else {
         ES.reportError(SymType.takeError());
-        R.failMaterialization();
+        R->failMaterialization();
         return;
       }
 
@@ -129,7 +120,7 @@ void RTDyldObjectLinkingLayer::emit(MaterializationResponsibility R,
       if (!SymFlagsOrErr) {
         // TODO: Test this error.
         ES.reportError(SymFlagsOrErr.takeError());
-        R.failMaterialization();
+        R->failMaterialization();
         return;
       }
 
@@ -139,46 +130,44 @@ void RTDyldObjectLinkingLayer::emit(MaterializationResponsibility R,
           InternalSymbols->insert(*SymName);
         else {
           ES.reportError(SymName.takeError());
-          R.failMaterialization();
+          R->failMaterialization();
           return;
         }
       }
     }
   }
 
-  auto K = R.getVModuleKey();
-  RuntimeDyld::MemoryManager *MemMgr = nullptr;
+  auto MemMgr = GetMemoryManager();
+  auto &MemMgrRef = *MemMgr;
 
-  // Create a record a memory manager for this object.
-  {
-    auto Tmp = GetMemoryManager();
-    std::lock_guard<std::mutex> Lock(RTDyldLayerMutex);
-    MemMgrs.push_back(std::move(Tmp));
-    MemMgr = MemMgrs.back().get();
-  }
+  // Switch to shared ownership of MR so that it can be captured by both
+  // lambdas below.
+  std::shared_ptr<MaterializationResponsibility> SharedR(std::move(R));
 
   JITDylibSearchOrderResolver Resolver(*SharedR);
 
   jitLinkForORC(
       object::OwningBinary<object::ObjectFile>(std::move(*Obj), std::move(O)),
-      *MemMgr, Resolver, ProcessAllSections,
-      [this, K, SharedR, MemMgr, InternalSymbols](
+      MemMgrRef, Resolver, ProcessAllSections,
+      [this, SharedR, &MemMgrRef, InternalSymbols](
           const object::ObjectFile &Obj,
-          std::unique_ptr<RuntimeDyld::LoadedObjectInfo> LoadedObjInfo,
+          RuntimeDyld::LoadedObjectInfo &LoadedObjInfo,
           std::map<StringRef, JITEvaluatedSymbol> ResolvedSymbols) {
-        return onObjLoad(K, *SharedR, Obj, MemMgr, std::move(LoadedObjInfo),
+        return onObjLoad(*SharedR, Obj, MemMgrRef, LoadedObjInfo,
                          ResolvedSymbols, *InternalSymbols);
       },
-      [this, K, SharedR, MemMgr](object::OwningBinary<object::ObjectFile> Obj,
-                                 Error Err) mutable {
-        onObjEmit(K, *SharedR, std::move(Obj), MemMgr, std::move(Err));
+      [this, SharedR, MemMgr = std::move(MemMgr)](
+          object::OwningBinary<object::ObjectFile> Obj,
+          std::unique_ptr<RuntimeDyld::LoadedObjectInfo> LoadedObjInfo,
+          Error Err) mutable {
+        onObjEmit(*SharedR, std::move(Obj), std::move(MemMgr),
+                  std::move(LoadedObjInfo), std::move(Err));
       });
 }
 
 void RTDyldObjectLinkingLayer::registerJITEventListener(JITEventListener &L) {
   std::lock_guard<std::mutex> Lock(RTDyldLayerMutex);
-  assert(llvm::none_of(EventListeners,
-                       [&](JITEventListener *O) { return O == &L; }) &&
+  assert(!llvm::is_contained(EventListeners, &L) &&
          "Listener has already been registered");
   EventListeners.push_back(&L);
 }
@@ -191,9 +180,9 @@ void RTDyldObjectLinkingLayer::unregisterJITEventListener(JITEventListener &L) {
 }
 
 Error RTDyldObjectLinkingLayer::onObjLoad(
-    VModuleKey K, MaterializationResponsibility &R,
-    const object::ObjectFile &Obj, RuntimeDyld::MemoryManager *MemMgr,
-    std::unique_ptr<RuntimeDyld::LoadedObjectInfo> LoadedObjInfo,
+    MaterializationResponsibility &R, const object::ObjectFile &Obj,
+    RuntimeDyld::MemoryManager &MemMgr,
+    RuntimeDyld::LoadedObjectInfo &LoadedObjInfo,
     std::map<StringRef, JITEvaluatedSymbol> Resolved,
     std::set<StringRef> &InternalSymbols) {
   SymbolFlagsMap ExtraSymbolsToClaim;
@@ -274,19 +263,16 @@ Error RTDyldObjectLinkingLayer::onObjLoad(
   }
 
   if (NotifyLoaded)
-    NotifyLoaded(K, Obj, *LoadedObjInfo);
-
-  std::lock_guard<std::mutex> Lock(RTDyldLayerMutex);
-  assert(!LoadedObjInfos.count(MemMgr) && "Duplicate loaded info for MemMgr");
-  LoadedObjInfos[MemMgr] = std::move(LoadedObjInfo);
+    NotifyLoaded(R, Obj, LoadedObjInfo);
 
   return Error::success();
 }
 
 void RTDyldObjectLinkingLayer::onObjEmit(
-    VModuleKey K, MaterializationResponsibility &R,
+    MaterializationResponsibility &R,
     object::OwningBinary<object::ObjectFile> O,
-    RuntimeDyld::MemoryManager *MemMgr, Error Err) {
+    std::unique_ptr<RuntimeDyld::MemoryManager> MemMgr,
+    std::unique_ptr<RuntimeDyld::LoadedObjectInfo> LoadedObjInfo, Error Err) {
   if (Err) {
     getExecutionSession().reportError(std::move(Err));
     R.failMaterialization();
@@ -306,27 +292,60 @@ void RTDyldObjectLinkingLayer::onObjEmit(
   // Run EventListener notifyLoaded callbacks.
   {
     std::lock_guard<std::mutex> Lock(RTDyldLayerMutex);
-    auto LOIItr = LoadedObjInfos.find(MemMgr);
-    assert(LOIItr != LoadedObjInfos.end() && "LoadedObjInfo missing");
     for (auto *L : EventListeners)
-      L->notifyObjectLoaded(
-          static_cast<uint64_t>(reinterpret_cast<uintptr_t>(MemMgr)), *Obj,
-          *LOIItr->second);
-    LoadedObjInfos.erase(MemMgr);
+      L->notifyObjectLoaded(pointerToJITTargetAddress(MemMgr.get()), *Obj,
+                            *LoadedObjInfo);
   }
 
   if (NotifyEmitted)
-    NotifyEmitted(K, std::move(ObjBuffer));
+    NotifyEmitted(R, std::move(ObjBuffer));
+
+  if (auto Err = R.withResourceKeyDo(
+          [&](ResourceKey K) { MemMgrs[K].push_back(std::move(MemMgr)); })) {
+    getExecutionSession().reportError(std::move(Err));
+    R.failMaterialization();
+  }
 }
 
-LegacyRTDyldObjectLinkingLayer::LegacyRTDyldObjectLinkingLayer(
-    ExecutionSession &ES, ResourcesGetter GetResources,
-    NotifyLoadedFtor NotifyLoaded, NotifyFinalizedFtor NotifyFinalized,
-    NotifyFreedFtor NotifyFreed)
-    : ES(ES), GetResources(std::move(GetResources)),
-      NotifyLoaded(std::move(NotifyLoaded)),
-      NotifyFinalized(std::move(NotifyFinalized)),
-      NotifyFreed(std::move(NotifyFreed)), ProcessAllSections(false) {}
+Error RTDyldObjectLinkingLayer::handleRemoveResources(ResourceKey K) {
+
+  std::vector<MemoryManagerUP> MemMgrsToRemove;
+
+  getExecutionSession().runSessionLocked([&] {
+    auto I = MemMgrs.find(K);
+    if (I != MemMgrs.end()) {
+      std::swap(MemMgrsToRemove, I->second);
+      MemMgrs.erase(I);
+    }
+  });
+
+  {
+    std::lock_guard<std::mutex> Lock(RTDyldLayerMutex);
+    for (auto &MemMgr : MemMgrsToRemove) {
+      for (auto *L : EventListeners)
+        L->notifyFreeingObject(pointerToJITTargetAddress(MemMgr.get()));
+      MemMgr->deregisterEHFrames();
+    }
+  }
+
+  return Error::success();
+}
+
+void RTDyldObjectLinkingLayer::handleTransferResources(ResourceKey DstKey,
+                                                       ResourceKey SrcKey) {
+  auto I = MemMgrs.find(SrcKey);
+  if (I != MemMgrs.end()) {
+    auto &SrcMemMgrs = I->second;
+    auto &DstMemMgrs = MemMgrs[DstKey];
+    DstMemMgrs.reserve(DstMemMgrs.size() + SrcMemMgrs.size());
+    for (auto &MemMgr : SrcMemMgrs)
+      DstMemMgrs.push_back(std::move(MemMgr));
+
+    // Erase SrcKey entry using value rather than iterator I: I may have been
+    // invalidated when we looked up DstKey.
+    MemMgrs.erase(SrcKey);
+  }
+}
 
 } // End namespace orc.
 } // End namespace llvm.
diff --git a/llvm/lib/ExecutionEngine/OrcError/OrcError.cpp b/llvm/lib/ExecutionEngine/Orc/Shared/OrcError.cpp
index cc99e154fbec..fdad90cbcfb7 100644
--- a/llvm/lib/ExecutionEngine/OrcError/OrcError.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/Shared/OrcError.cpp
@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/ExecutionEngine/Orc/OrcError.h"
+#include "llvm/ExecutionEngine/Orc/Shared/OrcError.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/ManagedStatic.h"
 
@@ -71,7 +71,7 @@ public:
 };
 
 static ManagedStatic<OrcErrorCategory> OrcErrCat;
-}
+} // namespace
 
 namespace llvm {
 namespace orc {
@@ -84,9 +84,8 @@ std::error_code orcError(OrcErrorCode ErrCode) {
   return std::error_code(static_cast<UT>(ErrCode), *OrcErrCat);
 }
 
-
 DuplicateDefinition::DuplicateDefinition(std::string SymbolName)
-  : SymbolName(std::move(SymbolName)) {}
+    : SymbolName(std::move(SymbolName)) {}
 
 std::error_code DuplicateDefinition::convertToErrorCode() const {
   return orcError(OrcErrorCode::DuplicateDefinition);
@@ -101,7 +100,7 @@ const std::string &DuplicateDefinition::getSymbolName() const {
 }
 
 JITSymbolNotFound::JITSymbolNotFound(std::string SymbolName)
-  : SymbolName(std::move(SymbolName)) {}
+    : SymbolName(std::move(SymbolName)) {}
 
 std::error_code JITSymbolNotFound::convertToErrorCode() const {
   typedef std::underlying_type<OrcErrorCode>::type UT;
@@ -117,5 +116,5 @@ const std::string &JITSymbolNotFound::getSymbolName() const {
   return SymbolName;
 }
 
-}
-}
+} // namespace orc
+} // namespace llvm
diff --git a/llvm/lib/ExecutionEngine/OrcError/RPCError.cpp b/llvm/lib/ExecutionEngine/Orc/Shared/RPCError.cpp
index 3cf78fd9f7ba..a55cb220f218 100644
--- a/llvm/lib/ExecutionEngine/OrcError/RPCError.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/Shared/RPCError.cpp
@@ -10,21 +10,21 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/ExecutionEngine/Orc/RPC/RPCUtils.h"
+#include "llvm/ExecutionEngine/Orc/Shared/RPCUtils.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/raw_ostream.h"
 
-#include <system_error>
 #include <string>
+#include <system_error>
 
-char llvm::orc::rpc::RPCFatalError::ID = 0;
-char llvm::orc::rpc::ConnectionClosed::ID = 0;
-char llvm::orc::rpc::ResponseAbandoned::ID = 0;
-char llvm::orc::rpc::CouldNotNegotiate::ID = 0;
+char llvm::orc::shared::RPCFatalError::ID = 0;
+char llvm::orc::shared::ConnectionClosed::ID = 0;
+char llvm::orc::shared::ResponseAbandoned::ID = 0;
+char llvm::orc::shared::CouldNotNegotiate::ID = 0;
 
 namespace llvm {
 namespace orc {
-namespace rpc {
+namespace shared {
 
 std::error_code ConnectionClosed::convertToErrorCode() const {
   return orcError(OrcErrorCode::RPCConnectionClosed);
@@ -53,7 +53,6 @@ void CouldNotNegotiate::log(raw_ostream &OS) const {
   OS << "Could not negotiate RPC function " << Signature;
 }
 
-
-} // end namespace rpc
+} // end namespace shared
 } // end namespace orc
 } // end namespace llvm
diff --git a/llvm/lib/ExecutionEngine/Orc/Shared/TargetProcessControlTypes.cpp b/llvm/lib/ExecutionEngine/Orc/Shared/TargetProcessControlTypes.cpp
new file mode 100644
index 000000000000..52d11f0741d4
--- /dev/null
+++ b/llvm/lib/ExecutionEngine/Orc/Shared/TargetProcessControlTypes.cpp
@@ -0,0 +1,44 @@
+//===---------- TargetProcessControlTypes.cpp - Shared TPC types ----------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// TargetProcessControl types.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ExecutionEngine/Orc/Shared/TargetProcessControlTypes.h"
+
+namespace llvm {
+namespace orc {
+namespace tpctypes {
+
+WrapperFunctionResult WrapperFunctionResult::from(StringRef S) {
+  CWrapperFunctionResult R;
+  zeroInit(R);
+  R.Size = S.size();
+  if (R.Size > sizeof(uint64_t)) {
+    R.Data.ValuePtr = new uint8_t[R.Size];
+    memcpy(R.Data.ValuePtr, S.data(), R.Size);
+    R.Destroy = destroyWithDeleteArray;
+  } else
+    memcpy(R.Data.Value, S.data(), R.Size);
+  return R;
+}
+
+void WrapperFunctionResult::destroyWithFree(CWrapperFunctionResultData Data,
+                                            uint64_t Size) {
+  free(Data.ValuePtr);
+}
+
+void WrapperFunctionResult::destroyWithDeleteArray(
+    CWrapperFunctionResultData Data, uint64_t Size) {
+  delete[] Data.ValuePtr;
+}
+
+} // end namespace tpctypes
+} // end namespace orc
+} // end namespace llvm
diff --git a/llvm/lib/ExecutionEngine/Orc/SpeculateAnalyses.cpp b/llvm/lib/ExecutionEngine/Orc/SpeculateAnalyses.cpp
index 7240c1ed0ce9..c2fa4466eab6 100644
--- a/llvm/lib/ExecutionEngine/Orc/SpeculateAnalyses.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/SpeculateAnalyses.cpp
@@ -106,11 +106,10 @@ BlockFreqQuery::ResultTy BlockFreqQuery::operator()(Function &F) {
 
   assert(IBBs.size() == BBFreqs.size() && "BB Count Mismatch");
 
-  llvm::sort(BBFreqs.begin(), BBFreqs.end(),
-             [](decltype(BBFreqs)::const_reference BBF,
-                decltype(BBFreqs)::const_reference BBS) {
-               return BBF.second > BBS.second ? true : false;
-             });
+  llvm::sort(BBFreqs, [](decltype(BBFreqs)::const_reference BBF,
+                         decltype(BBFreqs)::const_reference BBS) {
+    return BBF.second > BBS.second ? true : false;
+  });
 
   // ignoring number of direct calls in a BB
   auto Topk = numBBToGet(BBFreqs.size());
diff --git a/llvm/lib/ExecutionEngine/Orc/Speculation.cpp b/llvm/lib/ExecutionEngine/Orc/Speculation.cpp
index 0530b1a97b67..0b4755fe23cf 100644
--- a/llvm/lib/ExecutionEngine/Orc/Speculation.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/Speculation.cpp
@@ -16,9 +16,6 @@
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Type.h"
 #include "llvm/IR/Verifier.h"
-#include "llvm/Support/Debug.h"
-
-#include <vector>
 
 namespace llvm {
 
@@ -58,7 +55,7 @@ Error Speculator::addSpeculationRuntime(JITDylib &JD,
 // If two modules, share the same LLVMContext, different threads must
 // not access them concurrently without locking the associated LLVMContext
 // this implementation follows this contract.
-void IRSpeculationLayer::emit(MaterializationResponsibility R,
+void IRSpeculationLayer::emit(std::unique_ptr<MaterializationResponsibility> R,
                               ThreadSafeModule TSM) {
 
   assert(TSM && "Speculation Layer received Null Module ?");
@@ -130,7 +127,7 @@ void IRSpeculationLayer::emit(MaterializationResponsibility R,
           assert(Mutator.GetInsertBlock()->getParent() == &Fn &&
                  "IR builder association mismatch?");
           S.registerSymbols(internToJITSymbols(IRNames.getValue()),
-                            &R.getTargetJITDylib());
+                            &R->getTargetJITDylib());
         }
       }
     }
diff --git a/llvm/lib/ExecutionEngine/Orc/TPCDynamicLibrarySearchGenerator.cpp b/llvm/lib/ExecutionEngine/Orc/TPCDynamicLibrarySearchGenerator.cpp
new file mode 100644
index 000000000000..bbf3ada1d4ba
--- /dev/null
+++ b/llvm/lib/ExecutionEngine/Orc/TPCDynamicLibrarySearchGenerator.cpp
@@ -0,0 +1,70 @@
+//===---------------- TPCDynamicLibrarySearchGenerator.cpp ----------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ExecutionEngine/Orc/TPCDynamicLibrarySearchGenerator.h"
+
+namespace llvm {
+namespace orc {
+
+Expected<std::unique_ptr<TPCDynamicLibrarySearchGenerator>>
+TPCDynamicLibrarySearchGenerator::Load(TargetProcessControl &TPC,
+                                       const char *LibraryPath,
+                                       SymbolPredicate Allow) {
+  auto Handle = TPC.loadDylib(LibraryPath);
+  if (!Handle)
+    return Handle.takeError();
+
+  return std::make_unique<TPCDynamicLibrarySearchGenerator>(TPC, *Handle,
+                                                            std::move(Allow));
+}
+
+Error TPCDynamicLibrarySearchGenerator::tryToGenerate(
+    LookupState &LS, LookupKind K, JITDylib &JD,
+    JITDylibLookupFlags JDLookupFlags, const SymbolLookupSet &Symbols) {
+
+  if (Symbols.empty())
+    return Error::success();
+
+  SymbolLookupSet LookupSymbols;
+
+  for (auto &KV : Symbols) {
+    // Skip symbols that don't match the filter.
+    if (Allow && !Allow(KV.first))
+      continue;
+    LookupSymbols.add(KV.first, SymbolLookupFlags::WeaklyReferencedSymbol);
+  }
+
+  SymbolMap NewSymbols;
+
+  TargetProcessControl::LookupRequest Request(H, LookupSymbols);
+  auto Result = TPC.lookupSymbols(Request);
+  if (!Result)
+    return Result.takeError();
+
+  assert(Result->size() == 1 && "Results for more than one library returned");
+  assert(Result->front().size() == LookupSymbols.size() &&
+         "Result has incorrect number of elements");
+
+  auto ResultI = Result->front().begin();
+  for (auto &KV : LookupSymbols) {
+    if (*ResultI)
+      NewSymbols[KV.first] =
+          JITEvaluatedSymbol(*ResultI, JITSymbolFlags::Exported);
+    ++ResultI;
+  }
+
+  // If there were no resolved symbols bail out.
+  if (NewSymbols.empty())
+    return Error::success();
+
+  // Define resolved symbols.
+  return JD.define(absoluteSymbols(std::move(NewSymbols)));
+}
+
+} // end namespace orc
+} // end namespace llvm
diff --git a/llvm/lib/ExecutionEngine/Orc/TPCEHFrameRegistrar.cpp b/llvm/lib/ExecutionEngine/Orc/TPCEHFrameRegistrar.cpp
new file mode 100644
index 000000000000..4f901ce6d445
--- /dev/null
+++ b/llvm/lib/ExecutionEngine/Orc/TPCEHFrameRegistrar.cpp
@@ -0,0 +1,80 @@
+//===------ TPCEHFrameRegistrar.cpp - TPC-based eh-frame registration -----===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ExecutionEngine/Orc/TPCEHFrameRegistrar.h"
+#include "llvm/Support/BinaryStreamWriter.h"
+
+namespace llvm {
+namespace orc {
+
+Expected<std::unique_ptr<TPCEHFrameRegistrar>>
+TPCEHFrameRegistrar::Create(TargetProcessControl &TPC) {
+  // FIXME: Proper mangling here -- we really need to decouple linker mangling
+  // from DataLayout.
+
+  // Find the addresses of the registration/deregistration functions in the
+  // target process.
+  auto ProcessHandle = TPC.loadDylib(nullptr);
+  if (!ProcessHandle)
+    return ProcessHandle.takeError();
+
+  std::string RegisterWrapperName, DeregisterWrapperName;
+  if (TPC.getTargetTriple().isOSBinFormatMachO()) {
+    RegisterWrapperName += '_';
+    DeregisterWrapperName += '_';
+  }
+  RegisterWrapperName += "llvm_orc_registerEHFrameSectionWrapper";
+  DeregisterWrapperName += "llvm_orc_deregisterEHFrameSectionWrapper";
+
+  SymbolLookupSet RegistrationSymbols;
+  RegistrationSymbols.add(TPC.intern(RegisterWrapperName));
+  RegistrationSymbols.add(TPC.intern(DeregisterWrapperName));
+
+  auto Result = TPC.lookupSymbols({{*ProcessHandle, RegistrationSymbols}});
+  if (!Result)
+    return Result.takeError();
+
+  assert(Result->size() == 1 && "Unexpected number of dylibs in result");
+  assert((*Result)[0].size() == 2 &&
+         "Unexpected number of addresses in result");
+
+  auto RegisterEHFrameWrapperFnAddr = (*Result)[0][0];
+  auto DeregisterEHFrameWrapperFnAddr = (*Result)[0][1];
+
+  return std::make_unique<TPCEHFrameRegistrar>(
+      TPC, RegisterEHFrameWrapperFnAddr, DeregisterEHFrameWrapperFnAddr);
+}
+
+Error TPCEHFrameRegistrar::registerEHFrames(JITTargetAddress EHFrameSectionAddr,
+                                            size_t EHFrameSectionSize) {
+  constexpr size_t ArgBufferSize = sizeof(uint64_t) + sizeof(uint64_t);
+  uint8_t ArgBuffer[ArgBufferSize];
+  BinaryStreamWriter ArgWriter(
+      MutableArrayRef<uint8_t>(ArgBuffer, ArgBufferSize),
+      support::endianness::big);
+  cantFail(ArgWriter.writeInteger(static_cast<uint64_t>(EHFrameSectionAddr)));
+  cantFail(ArgWriter.writeInteger(static_cast<uint64_t>(EHFrameSectionSize)));
+
+  return TPC.runWrapper(RegisterEHFrameWrapperFnAddr, ArgBuffer).takeError();
+}
+
+Error TPCEHFrameRegistrar::deregisterEHFrames(
+    JITTargetAddress EHFrameSectionAddr, size_t EHFrameSectionSize) {
+  constexpr size_t ArgBufferSize = sizeof(uint64_t) + sizeof(uint64_t);
+  uint8_t ArgBuffer[ArgBufferSize];
+  BinaryStreamWriter ArgWriter(
+      MutableArrayRef<uint8_t>(ArgBuffer, ArgBufferSize),
+      support::endianness::big);
+  cantFail(ArgWriter.writeInteger(static_cast<uint64_t>(EHFrameSectionAddr)));
+  cantFail(ArgWriter.writeInteger(static_cast<uint64_t>(EHFrameSectionSize)));
+
+  return TPC.runWrapper(DeregisterEHFrameWrapperFnAddr, ArgBuffer).takeError();
+}
+
+} // end namespace orc
+} // end namespace llvm
diff --git a/llvm/lib/ExecutionEngine/Orc/TPCIndirectionUtils.cpp b/llvm/lib/ExecutionEngine/Orc/TPCIndirectionUtils.cpp
new file mode 100644
index 000000000000..7989ec41952d
--- /dev/null
+++ b/llvm/lib/ExecutionEngine/Orc/TPCIndirectionUtils.cpp
@@ -0,0 +1,423 @@
+//===------ TargetProcessControl.cpp -- Target process control APIs -------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ExecutionEngine/Orc/TPCIndirectionUtils.h"
+
+#include "llvm/ExecutionEngine/Orc/TargetProcessControl.h"
+#include "llvm/Support/MathExtras.h"
+
+#include <future>
+
+using namespace llvm;
+using namespace llvm::orc;
+
+namespace llvm {
+namespace orc {
+
+class TPCIndirectionUtilsAccess {
+public:
+  using IndirectStubInfo = TPCIndirectionUtils::IndirectStubInfo;
+  using IndirectStubInfoVector = TPCIndirectionUtils::IndirectStubInfoVector;
+
+  static Expected<IndirectStubInfoVector>
+  getIndirectStubs(TPCIndirectionUtils &TPCIU, unsigned NumStubs) {
+    return TPCIU.getIndirectStubs(NumStubs);
+  };
+};
+
+} // end namespace orc
+} // end namespace llvm
+
+namespace {
+
+class TPCTrampolinePool : public TrampolinePool {
+public:
+  TPCTrampolinePool(TPCIndirectionUtils &TPCIU);
+  Error deallocatePool();
+
+protected:
+  Error grow() override;
+
+  using Allocation = jitlink::JITLinkMemoryManager::Allocation;
+
+  TPCIndirectionUtils &TPCIU;
+  unsigned TrampolineSize = 0;
+  unsigned TrampolinesPerPage = 0;
+  std::vector<std::unique_ptr<Allocation>> TrampolineBlocks;
+};
+
+class TPCIndirectStubsManager : public IndirectStubsManager,
+                                private TPCIndirectionUtilsAccess {
+public:
+  TPCIndirectStubsManager(TPCIndirectionUtils &TPCIU) : TPCIU(TPCIU) {}
+
+  Error deallocateStubs();
+
+  Error createStub(StringRef StubName, JITTargetAddress StubAddr,
+                   JITSymbolFlags StubFlags) override;
+
+  Error createStubs(const StubInitsMap &StubInits) override;
+
+  JITEvaluatedSymbol findStub(StringRef Name, bool ExportedStubsOnly) override;
+
+  JITEvaluatedSymbol findPointer(StringRef Name) override;
+
+  Error updatePointer(StringRef Name, JITTargetAddress NewAddr) override;
+
+private:
+  using StubInfo = std::pair<IndirectStubInfo, JITSymbolFlags>;
+
+  std::mutex ISMMutex;
+  TPCIndirectionUtils &TPCIU;
+  StringMap<StubInfo> StubInfos;
+};
+
+TPCTrampolinePool::TPCTrampolinePool(TPCIndirectionUtils &TPCIU)
+    : TPCIU(TPCIU) {
+  auto &TPC = TPCIU.getTargetProcessControl();
+  auto &ABI = TPCIU.getABISupport();
+
+  TrampolineSize = ABI.getTrampolineSize();
+  TrampolinesPerPage =
+      (TPC.getPageSize() - ABI.getPointerSize()) / TrampolineSize;
+}
+
+Error TPCTrampolinePool::deallocatePool() {
+  Error Err = Error::success();
+  for (auto &Alloc : TrampolineBlocks)
+    Err = joinErrors(std::move(Err), Alloc->deallocate());
+  return Err;
+}
+
+Error TPCTrampolinePool::grow() {
+  assert(AvailableTrampolines.empty() &&
+         "Grow called with trampolines still available");
+
+  auto ResolverAddress = TPCIU.getResolverBlockAddress();
+  assert(ResolverAddress && "Resolver address can not be null");
+
+  auto &TPC = TPCIU.getTargetProcessControl();
+  constexpr auto TrampolinePagePermissions =
+      static_cast<sys::Memory::ProtectionFlags>(sys::Memory::MF_READ |
+                                                sys::Memory::MF_EXEC);
+  auto PageSize = TPC.getPageSize();
+  jitlink::JITLinkMemoryManager::SegmentsRequestMap Request;
+  Request[TrampolinePagePermissions] = {PageSize, static_cast<size_t>(PageSize),
+                                        0};
+  auto Alloc = TPC.getMemMgr().allocate(nullptr, Request);
+
+  if (!Alloc)
+    return Alloc.takeError();
+
+  unsigned NumTrampolines = TrampolinesPerPage;
+
+  auto WorkingMemory = (*Alloc)->getWorkingMemory(TrampolinePagePermissions);
+  auto TargetAddress = (*Alloc)->getTargetMemory(TrampolinePagePermissions);
+
+  TPCIU.getABISupport().writeTrampolines(WorkingMemory.data(), TargetAddress,
+                                         ResolverAddress, NumTrampolines);
+
+  auto TargetAddr = (*Alloc)->getTargetMemory(TrampolinePagePermissions);
+  for (unsigned I = 0; I < NumTrampolines; ++I)
+    AvailableTrampolines.push_back(TargetAddr + (I * TrampolineSize));
+
+  if (auto Err = (*Alloc)->finalize())
+    return Err;
+
+  TrampolineBlocks.push_back(std::move(*Alloc));
+
+  return Error::success();
+}
+
+Error TPCIndirectStubsManager::createStub(StringRef StubName,
+                                          JITTargetAddress StubAddr,
+                                          JITSymbolFlags StubFlags) {
+  StubInitsMap SIM;
+  SIM[StubName] = std::make_pair(StubAddr, StubFlags);
+  return createStubs(SIM);
+}
+
+Error TPCIndirectStubsManager::createStubs(const StubInitsMap &StubInits) {
+  auto AvailableStubInfos = getIndirectStubs(TPCIU, StubInits.size());
+  if (!AvailableStubInfos)
+    return AvailableStubInfos.takeError();
+
+  {
+    std::lock_guard<std::mutex> Lock(ISMMutex);
+    unsigned ASIdx = 0;
+    for (auto &SI : StubInits) {
+      auto &A = (*AvailableStubInfos)[ASIdx++];
+      StubInfos[SI.first()] = std::make_pair(A, SI.second.second);
+    }
+  }
+
+  auto &MemAccess = TPCIU.getTargetProcessControl().getMemoryAccess();
+  switch (TPCIU.getABISupport().getPointerSize()) {
+  case 4: {
+    unsigned ASIdx = 0;
+    std::vector<tpctypes::UInt32Write> PtrUpdates;
+    for (auto &SI : StubInits)
+      PtrUpdates.push_back({(*AvailableStubInfos)[ASIdx++].PointerAddress,
+                            static_cast<uint32_t>(SI.second.first)});
+    return MemAccess.writeUInt32s(PtrUpdates);
+  }
+  case 8: {
+    unsigned ASIdx = 0;
+    std::vector<tpctypes::UInt64Write> PtrUpdates;
+    for (auto &SI : StubInits)
+      PtrUpdates.push_back({(*AvailableStubInfos)[ASIdx++].PointerAddress,
+                            static_cast<uint64_t>(SI.second.first)});
+    return MemAccess.writeUInt64s(PtrUpdates);
+  }
+  default:
+    return make_error<StringError>("Unsupported pointer size",
+                                   inconvertibleErrorCode());
+  }
+}
+
+JITEvaluatedSymbol TPCIndirectStubsManager::findStub(StringRef Name,
+                                                     bool ExportedStubsOnly) {
+  std::lock_guard<std::mutex> Lock(ISMMutex);
+  auto I = StubInfos.find(Name);
+  if (I == StubInfos.end())
+    return nullptr;
+  return {I->second.first.StubAddress, I->second.second};
+}
+
+JITEvaluatedSymbol TPCIndirectStubsManager::findPointer(StringRef Name) {
+  std::lock_guard<std::mutex> Lock(ISMMutex);
+  auto I = StubInfos.find(Name);
+  if (I == StubInfos.end())
+    return nullptr;
+  return {I->second.first.PointerAddress, I->second.second};
+}
+
+Error TPCIndirectStubsManager::updatePointer(StringRef Name,
+                                             JITTargetAddress NewAddr) {
+
+  JITTargetAddress PtrAddr = 0;
+  {
+    std::lock_guard<std::mutex> Lock(ISMMutex);
+    auto I = StubInfos.find(Name);
+    if (I == StubInfos.end())
+      return make_error<StringError>("Unknown stub name",
+                                     inconvertibleErrorCode());
+    PtrAddr = I->second.first.PointerAddress;
+  }
+
+  auto &MemAccess = TPCIU.getTargetProcessControl().getMemoryAccess();
+  switch (TPCIU.getABISupport().getPointerSize()) {
+  case 4: {
+    tpctypes::UInt32Write PUpdate(PtrAddr, NewAddr);
+    return MemAccess.writeUInt32s(PUpdate);
+  }
+  case 8: {
+    tpctypes::UInt64Write PUpdate(PtrAddr, NewAddr);
+    return MemAccess.writeUInt64s(PUpdate);
+  }
+  default:
+    return make_error<StringError>("Unsupported pointer size",
+                                   inconvertibleErrorCode());
+  }
+}
+
+} // end anonymous namespace.
+
+namespace llvm {
+namespace orc {
+
+TPCIndirectionUtils::ABISupport::~ABISupport() {}
+
+Expected<std::unique_ptr<TPCIndirectionUtils>>
+TPCIndirectionUtils::Create(TargetProcessControl &TPC) {
+  const auto &TT = TPC.getTargetTriple();
+  switch (TT.getArch()) {
+  default:
+    return make_error<StringError>(
+        std::string("No TPCIndirectionUtils available for ") + TT.str(),
+        inconvertibleErrorCode());
+  case Triple::aarch64:
+  case Triple::aarch64_32:
+    return CreateWithABI<OrcAArch64>(TPC);
+
+  case Triple::x86:
+    return CreateWithABI<OrcI386>(TPC);
+
+  case Triple::mips:
+    return CreateWithABI<OrcMips32Be>(TPC);
+
+  case Triple::mipsel:
+    return CreateWithABI<OrcMips32Le>(TPC);
+
+  case Triple::mips64:
+  case Triple::mips64el:
+    return CreateWithABI<OrcMips64>(TPC);
+
+  case Triple::x86_64:
+    if (TT.getOS() == Triple::OSType::Win32)
+      return CreateWithABI<OrcX86_64_Win32>(TPC);
+    else
+      return CreateWithABI<OrcX86_64_SysV>(TPC);
+  }
+}
+
+Error TPCIndirectionUtils::cleanup() {
+  Error Err = Error::success();
+
+  for (auto &A : IndirectStubAllocs)
+    Err = joinErrors(std::move(Err), A->deallocate());
+
+  if (TP)
+    Err = joinErrors(std::move(Err),
+                     static_cast<TPCTrampolinePool &>(*TP).deallocatePool());
+
+  if (ResolverBlock)
+    Err = joinErrors(std::move(Err), ResolverBlock->deallocate());
+
+  return Err;
+}
+
+Expected<JITTargetAddress>
+TPCIndirectionUtils::writeResolverBlock(JITTargetAddress ReentryFnAddr,
+                                        JITTargetAddress ReentryCtxAddr) {
+  assert(ABI && "ABI can not be null");
+  constexpr auto ResolverBlockPermissions =
+      static_cast<sys::Memory::ProtectionFlags>(sys::Memory::MF_READ |
+                                                sys::Memory::MF_EXEC);
+  auto ResolverSize = ABI->getResolverCodeSize();
+
+  jitlink::JITLinkMemoryManager::SegmentsRequestMap Request;
+  Request[ResolverBlockPermissions] = {TPC.getPageSize(),
+                                       static_cast<size_t>(ResolverSize), 0};
+  auto Alloc = TPC.getMemMgr().allocate(nullptr, Request);
+  if (!Alloc)
+    return Alloc.takeError();
+
+  auto WorkingMemory = (*Alloc)->getWorkingMemory(ResolverBlockPermissions);
+  ResolverBlockAddr = (*Alloc)->getTargetMemory(ResolverBlockPermissions);
+  ABI->writeResolverCode(WorkingMemory.data(), ResolverBlockAddr, ReentryFnAddr,
+                         ReentryCtxAddr);
+
+  if (auto Err = (*Alloc)->finalize())
+    return std::move(Err);
+
+  ResolverBlock = std::move(*Alloc);
+  return ResolverBlockAddr;
+}
+
+std::unique_ptr<IndirectStubsManager>
+TPCIndirectionUtils::createIndirectStubsManager() {
+  return std::make_unique<TPCIndirectStubsManager>(*this);
+}
+
+TrampolinePool &TPCIndirectionUtils::getTrampolinePool() {
+  if (!TP)
+    TP = std::make_unique<TPCTrampolinePool>(*this);
+  return *TP;
+}
+
+LazyCallThroughManager &TPCIndirectionUtils::createLazyCallThroughManager(
+    ExecutionSession &ES, JITTargetAddress ErrorHandlerAddr) {
+  assert(!LCTM &&
+         "createLazyCallThroughManager can not have been called before");
+  LCTM = std::make_unique<LazyCallThroughManager>(ES, ErrorHandlerAddr,
+                                                  &getTrampolinePool());
+  return *LCTM;
+}
+
+TPCIndirectionUtils::TPCIndirectionUtils(TargetProcessControl &TPC,
+                                         std::unique_ptr<ABISupport> ABI)
+    : TPC(TPC), ABI(std::move(ABI)) {
+  assert(this->ABI && "ABI can not be null");
+
+  assert(TPC.getPageSize() > getABISupport().getStubSize() &&
+         "Stubs larger than one page are not supported");
+}
+
+Expected<TPCIndirectionUtils::IndirectStubInfoVector>
+TPCIndirectionUtils::getIndirectStubs(unsigned NumStubs) {
+
+  std::lock_guard<std::mutex> Lock(TPCUIMutex);
+
+  // If there aren't enough stubs available then allocate some more.
+  if (NumStubs > AvailableIndirectStubs.size()) {
+    auto NumStubsToAllocate = NumStubs;
+    auto PageSize = TPC.getPageSize();
+    auto StubBytes = alignTo(NumStubsToAllocate * ABI->getStubSize(), PageSize);
+    NumStubsToAllocate = StubBytes / ABI->getStubSize();
+    auto PointerBytes =
+        alignTo(NumStubsToAllocate * ABI->getPointerSize(), PageSize);
+
+    constexpr auto StubPagePermissions =
+        static_cast<sys::Memory::ProtectionFlags>(sys::Memory::MF_READ |
+                                                  sys::Memory::MF_EXEC);
+    constexpr auto PointerPagePermissions =
+        static_cast<sys::Memory::ProtectionFlags>(sys::Memory::MF_READ |
+                                                  sys::Memory::MF_WRITE);
+
+    jitlink::JITLinkMemoryManager::SegmentsRequestMap Request;
+    Request[StubPagePermissions] = {PageSize, static_cast<size_t>(StubBytes),
+                                    0};
+    Request[PointerPagePermissions] = {PageSize, 0, PointerBytes};
+    auto Alloc = TPC.getMemMgr().allocate(nullptr, Request);
+    if (!Alloc)
+      return Alloc.takeError();
+
+    auto StubTargetAddr = (*Alloc)->getTargetMemory(StubPagePermissions);
+    auto PointerTargetAddr = (*Alloc)->getTargetMemory(PointerPagePermissions);
+
+    ABI->writeIndirectStubsBlock(
+        (*Alloc)->getWorkingMemory(StubPagePermissions).data(), StubTargetAddr,
+        PointerTargetAddr, NumStubsToAllocate);
+
+    if (auto Err = (*Alloc)->finalize())
+      return std::move(Err);
+
+    for (unsigned I = 0; I != NumStubsToAllocate; ++I) {
+      AvailableIndirectStubs.push_back(
+          IndirectStubInfo(StubTargetAddr, PointerTargetAddr));
+      StubTargetAddr += ABI->getStubSize();
+      PointerTargetAddr += ABI->getPointerSize();
+    }
+
+    IndirectStubAllocs.push_back(std::move(*Alloc));
+  }
+
+  assert(NumStubs <= AvailableIndirectStubs.size() &&
+         "Sufficient stubs should have been allocated above");
+
+  IndirectStubInfoVector Result;
+  while (NumStubs--) {
+    Result.push_back(AvailableIndirectStubs.back());
+    AvailableIndirectStubs.pop_back();
+  }
+
+  return std::move(Result);
+}
+
+static JITTargetAddress reentry(JITTargetAddress LCTMAddr,
+                                JITTargetAddress TrampolineAddr) {
+  auto &LCTM = *jitTargetAddressToPointer<LazyCallThroughManager *>(LCTMAddr);
+  std::promise<JITTargetAddress> LandingAddrP;
+  auto LandingAddrF = LandingAddrP.get_future();
+  LCTM.resolveTrampolineLandingAddress(
+      TrampolineAddr,
+      [&](JITTargetAddress Addr) { LandingAddrP.set_value(Addr); });
+  return LandingAddrF.get();
+}
+
+Error setUpInProcessLCTMReentryViaTPCIU(TPCIndirectionUtils &TPCIU) {
+  auto &LCTM = TPCIU.getLazyCallThroughManager();
+  return TPCIU
+      .writeResolverBlock(pointerToJITTargetAddress(&reentry),
+                          pointerToJITTargetAddress(&LCTM))
+      .takeError();
+}
+
+} // end namespace orc
+} // end namespace llvm
diff --git a/llvm/lib/ExecutionEngine/Orc/TargetProcess/RegisterEHFrames.cpp b/llvm/lib/ExecutionEngine/Orc/TargetProcess/RegisterEHFrames.cpp
new file mode 100644
index 000000000000..aff7296cb6e3
--- /dev/null
+++ b/llvm/lib/ExecutionEngine/Orc/TargetProcess/RegisterEHFrames.cpp
@@ -0,0 +1,208 @@
+//===--------- RegisterEHFrames.cpp - Register EH frame sections ----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ExecutionEngine/Orc/TargetProcess/RegisterEHFrames.h"
+
+#include "llvm/Config/config.h"
+#include "llvm/ExecutionEngine/JITSymbol.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/DynamicLibrary.h"
+#include "llvm/Support/raw_ostream.h"
+
+#include "llvm/Support/FormatVariadic.h"
+
+#define DEBUG_TYPE "orc"
+
+using namespace llvm;
+using namespace llvm::orc;
+using namespace llvm::orc::tpctypes;
+
+namespace llvm {
+namespace orc {
+
+#if defined(HAVE_REGISTER_FRAME) && defined(HAVE_DEREGISTER_FRAME) &&          \
+    !defined(__SEH__) && !defined(__USING_SJLJ_EXCEPTIONS__)
+
+extern "C" void __register_frame(const void *);
+extern "C" void __deregister_frame(const void *);
+
+Error registerFrameWrapper(const void *P) {
+  __register_frame(P);
+  return Error::success();
+}
+
+Error deregisterFrameWrapper(const void *P) {
+  __deregister_frame(P);
+  return Error::success();
+}
+
+#else
+
+// The building compiler does not have __(de)register_frame but
+// it may be found at runtime in a dynamically-loaded library.
+// For example, this happens when building LLVM with Visual C++
+// but using the MingW runtime.
+static Error registerFrameWrapper(const void *P) {
+  static void((*RegisterFrame)(const void *)) = 0;
+
+  if (!RegisterFrame)
+    *(void **)&RegisterFrame =
+        llvm::sys::DynamicLibrary::SearchForAddressOfSymbol("__register_frame");
+
+  if (RegisterFrame) {
+    RegisterFrame(P);
+    return Error::success();
+  }
+
+  return make_error<StringError>("could not register eh-frame: "
+                                 "__register_frame function not found",
+                                 inconvertibleErrorCode());
+}
+
+static Error deregisterFrameWrapper(const void *P) {
+  static void((*DeregisterFrame)(const void *)) = 0;
+
+  if (!DeregisterFrame)
+    *(void **)&DeregisterFrame =
+        llvm::sys::DynamicLibrary::SearchForAddressOfSymbol(
+            "__deregister_frame");
+
+  if (DeregisterFrame) {
+    DeregisterFrame(P);
+    return Error::success();
+  }
+
+  return make_error<StringError>("could not deregister eh-frame: "
+                                 "__deregister_frame function not found",
+                                 inconvertibleErrorCode());
+}
+#endif
+
+#ifdef __APPLE__
+
+template <typename HandleFDEFn>
+Error walkAppleEHFrameSection(const char *const SectionStart,
+                              size_t SectionSize, HandleFDEFn HandleFDE) {
+  const char *CurCFIRecord = SectionStart;
+  const char *End = SectionStart + SectionSize;
+  uint64_t Size = *reinterpret_cast<const uint32_t *>(CurCFIRecord);
+
+  while (CurCFIRecord != End && Size != 0) {
+    const char *OffsetField = CurCFIRecord + (Size == 0xffffffff ? 12 : 4);
+    if (Size == 0xffffffff)
+      Size = *reinterpret_cast<const uint64_t *>(CurCFIRecord + 4) + 12;
+    else
+      Size += 4;
+    uint32_t Offset = *reinterpret_cast<const uint32_t *>(OffsetField);
+
+    LLVM_DEBUG({
+      dbgs() << "Registering eh-frame section:\n";
+      dbgs() << "Processing " << (Offset ? "FDE" : "CIE") << " @"
+             << (void *)CurCFIRecord << ": [";
+      for (unsigned I = 0; I < Size; ++I)
+        dbgs() << format(" 0x%02" PRIx8, *(CurCFIRecord + I));
+      dbgs() << " ]\n";
+    });
+
+    if (Offset != 0)
+      if (auto Err = HandleFDE(CurCFIRecord))
+        return Err;
+
+    CurCFIRecord += Size;
+
+    Size = *reinterpret_cast<const uint32_t *>(CurCFIRecord);
+  }
+
+  return Error::success();
+}
+
+#endif // __APPLE__
+
+Error registerEHFrameSection(const void *EHFrameSectionAddr,
+                             size_t EHFrameSectionSize) {
+#ifdef __APPLE__
+  // On Darwin __register_frame has to be called for each FDE entry.
+  return walkAppleEHFrameSection(static_cast<const char *>(EHFrameSectionAddr),
+                                 EHFrameSectionSize, registerFrameWrapper);
+#else
+  // On Linux __register_frame takes a single argument:
+  // a pointer to the start of the .eh_frame section.
+
+  // How can it find the end? Because crtendS.o is linked
+  // in and it has an .eh_frame section with four zero chars.
+  return registerFrameWrapper(EHFrameSectionAddr);
+#endif
+}
+
+Error deregisterEHFrameSection(const void *EHFrameSectionAddr,
+                               size_t EHFrameSectionSize) {
+#ifdef __APPLE__
+  return walkAppleEHFrameSection(static_cast<const char *>(EHFrameSectionAddr),
+                                 EHFrameSectionSize, deregisterFrameWrapper);
+#else
+  return deregisterFrameWrapper(EHFrameSectionAddr);
+#endif
+}
+
+} // end namespace orc
+} // end namespace llvm
+
+extern "C" CWrapperFunctionResult
+llvm_orc_registerEHFrameSectionWrapper(uint8_t *Data, uint64_t Size) {
+  if (Size != sizeof(uint64_t) + sizeof(uint64_t))
+    return WrapperFunctionResult::from(
+               "Invalid arguments to llvm_orc_registerEHFrameSectionWrapper")
+        .release();
+
+  uint64_t EHFrameSectionAddr;
+  uint64_t EHFrameSectionSize;
+
+  {
+    BinaryStreamReader ArgReader(ArrayRef<uint8_t>(Data, Size),
+                                 support::endianness::big);
+    cantFail(ArgReader.readInteger(EHFrameSectionAddr));
+    cantFail(ArgReader.readInteger(EHFrameSectionSize));
+  }
+
+  if (auto Err = registerEHFrameSection(
+          jitTargetAddressToPointer<void *>(EHFrameSectionAddr),
+          EHFrameSectionSize)) {
+    auto ErrMsg = toString(std::move(Err));
+    return WrapperFunctionResult::from(ErrMsg).release();
+  }
+  return WrapperFunctionResult().release();
+}
+
+extern "C" CWrapperFunctionResult
+llvm_orc_deregisterEHFrameSectionWrapper(uint8_t *Data, uint64_t Size) {
+  if (Size != sizeof(uint64_t) + sizeof(uint64_t))
+    return WrapperFunctionResult::from(
+               "Invalid arguments to llvm_orc_registerEHFrameSectionWrapper")
+        .release();
+
+  uint64_t EHFrameSectionAddr;
+  uint64_t EHFrameSectionSize;
+
+  {
+    BinaryStreamReader ArgReader(ArrayRef<uint8_t>(Data, Size),
+                                 support::endianness::big);
+    cantFail(ArgReader.readInteger(EHFrameSectionAddr));
+    cantFail(ArgReader.readInteger(EHFrameSectionSize));
+  }
+
+  if (auto Err = deregisterEHFrameSection(
+          jitTargetAddressToPointer<void *>(EHFrameSectionAddr),
+          EHFrameSectionSize)) {
+    auto ErrMsg = toString(std::move(Err));
+    return WrapperFunctionResult::from(ErrMsg).release();
+  }
+  return WrapperFunctionResult().release();
+}
diff --git a/llvm/lib/ExecutionEngine/Orc/TargetProcess/TargetExecutionUtils.cpp b/llvm/lib/ExecutionEngine/Orc/TargetProcess/TargetExecutionUtils.cpp
new file mode 100644
index 000000000000..a8e6c049cf4b
--- /dev/null
+++ b/llvm/lib/ExecutionEngine/Orc/TargetProcess/TargetExecutionUtils.cpp
@@ -0,0 +1,43 @@
+//===--- TargetExecutionUtils.cpp - Execution utils for target processes --===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ExecutionEngine/Orc/TargetProcess/TargetExecutionUtils.h"
+
+#include <vector>
+
+namespace llvm {
+namespace orc {
+
+int runAsMain(int (*Main)(int, char *[]), ArrayRef<std::string> Args,
+              Optional<StringRef> ProgramName) {
+  std::vector<std::unique_ptr<char[]>> ArgVStorage;
+  std::vector<char *> ArgV;
+
+  ArgVStorage.reserve(Args.size() + (ProgramName ? 1 : 0));
+  ArgV.reserve(Args.size() + 1 + (ProgramName ? 1 : 0));
+
+  if (ProgramName) {
+    ArgVStorage.push_back(std::make_unique<char[]>(ProgramName->size() + 1));
+    llvm::copy(*ProgramName, &ArgVStorage.back()[0]);
+    ArgVStorage.back()[ProgramName->size()] = '\0';
+    ArgV.push_back(ArgVStorage.back().get());
+  }
+
+  for (const auto &Arg : Args) {
+    ArgVStorage.push_back(std::make_unique<char[]>(Arg.size() + 1));
+    llvm::copy(Arg, &ArgVStorage.back()[0]);
+    ArgVStorage.back()[Arg.size()] = '\0';
+    ArgV.push_back(ArgVStorage.back().get());
+  }
+  ArgV.push_back(nullptr);
+
+  return Main(Args.size() + !!ProgramName, ArgV.data());
+}
+
+} // End namespace orc.
+} // End namespace llvm.
diff --git a/llvm/lib/ExecutionEngine/Orc/TargetProcessControl.cpp b/llvm/lib/ExecutionEngine/Orc/TargetProcessControl.cpp
new file mode 100644
index 000000000000..7bf874e88c26
--- /dev/null
+++ b/llvm/lib/ExecutionEngine/Orc/TargetProcessControl.cpp
@@ -0,0 +1,153 @@
+//===------ TargetProcessControl.cpp -- Target process control APIs -------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ExecutionEngine/Orc/TargetProcessControl.h"
+
+#include "llvm/ExecutionEngine/Orc/Core.h"
+#include "llvm/ExecutionEngine/Orc/TargetProcess/TargetExecutionUtils.h"
+#include "llvm/Support/Host.h"
+#include "llvm/Support/Process.h"
+
+#include <mutex>
+
+namespace llvm {
+namespace orc {
+
+TargetProcessControl::MemoryAccess::~MemoryAccess() {}
+
+TargetProcessControl::~TargetProcessControl() {}
+
+SelfTargetProcessControl::SelfTargetProcessControl(
+    std::shared_ptr<SymbolStringPool> SSP, Triple TargetTriple,
+    unsigned PageSize, std::unique_ptr<jitlink::JITLinkMemoryManager> MemMgr)
+    : TargetProcessControl(std::move(SSP)) {
+
+  OwnedMemMgr = std::move(MemMgr);
+  if (!OwnedMemMgr)
+    OwnedMemMgr = std::make_unique<jitlink::InProcessMemoryManager>();
+
+  this->TargetTriple = std::move(TargetTriple);
+  this->PageSize = PageSize;
+  this->MemMgr = OwnedMemMgr.get();
+  this->MemAccess = this;
+  if (this->TargetTriple.isOSBinFormatMachO())
+    GlobalManglingPrefix = '_';
+}
+
+Expected<std::unique_ptr<SelfTargetProcessControl>>
+SelfTargetProcessControl::Create(
+    std::shared_ptr<SymbolStringPool> SSP,
+    std::unique_ptr<jitlink::JITLinkMemoryManager> MemMgr) {
+  auto PageSize = sys::Process::getPageSize();
+  if (!PageSize)
+    return PageSize.takeError();
+
+  Triple TT(sys::getProcessTriple());
+
+  return std::make_unique<SelfTargetProcessControl>(
+      std::move(SSP), std::move(TT), *PageSize, std::move(MemMgr));
+}
+
+Expected<tpctypes::DylibHandle>
+SelfTargetProcessControl::loadDylib(const char *DylibPath) {
+  std::string ErrMsg;
+  auto Dylib = std::make_unique<sys::DynamicLibrary>(
+      sys::DynamicLibrary::getPermanentLibrary(DylibPath, &ErrMsg));
+  if (!Dylib->isValid())
+    return make_error<StringError>(std::move(ErrMsg), inconvertibleErrorCode());
+  DynamicLibraries.push_back(std::move(Dylib));
+  return pointerToJITTargetAddress(DynamicLibraries.back().get());
+}
+
+Expected<std::vector<tpctypes::LookupResult>>
+SelfTargetProcessControl::lookupSymbols(ArrayRef<LookupRequest> Request) {
+  std::vector<tpctypes::LookupResult> R;
+
+  for (auto &Elem : Request) {
+    auto *Dylib = jitTargetAddressToPointer<sys::DynamicLibrary *>(Elem.Handle);
+    assert(llvm::any_of(DynamicLibraries,
+                        [=](const std::unique_ptr<sys::DynamicLibrary> &DL) {
+                          return DL.get() == Dylib;
+                        }) &&
+           "Invalid handle");
+
+    R.push_back(std::vector<JITTargetAddress>());
+    for (auto &KV : Elem.Symbols) {
+      auto &Sym = KV.first;
+      std::string Tmp((*Sym).data() + !!GlobalManglingPrefix,
+                      (*Sym).size() - !!GlobalManglingPrefix);
+      void *Addr = Dylib->getAddressOfSymbol(Tmp.c_str());
+      if (!Addr && KV.second == SymbolLookupFlags::RequiredSymbol) {
+        // FIXME: Collect all failing symbols before erroring out.
+        SymbolNameVector MissingSymbols;
+        MissingSymbols.push_back(Sym);
+        return make_error<SymbolsNotFound>(std::move(MissingSymbols));
+      }
+      R.back().push_back(pointerToJITTargetAddress(Addr));
+    }
+  }
+
+  return R;
+}
+
+Expected<int32_t>
+SelfTargetProcessControl::runAsMain(JITTargetAddress MainFnAddr,
+                                    ArrayRef<std::string> Args) {
+  using MainTy = int (*)(int, char *[]);
+  return orc::runAsMain(jitTargetAddressToFunction<MainTy>(MainFnAddr), Args);
+}
+
+Expected<tpctypes::WrapperFunctionResult>
+SelfTargetProcessControl::runWrapper(JITTargetAddress WrapperFnAddr,
+                                     ArrayRef<uint8_t> ArgBuffer) {
+  using WrapperFnTy =
+      tpctypes::CWrapperFunctionResult (*)(const uint8_t *Data, uint64_t Size);
+  auto *WrapperFn = jitTargetAddressToFunction<WrapperFnTy>(WrapperFnAddr);
+  return WrapperFn(ArgBuffer.data(), ArgBuffer.size());
+}
+
+Error SelfTargetProcessControl::disconnect() { return Error::success(); }
+
+void SelfTargetProcessControl::writeUInt8s(ArrayRef<tpctypes::UInt8Write> Ws,
+                                           WriteResultFn OnWriteComplete) {
+  for (auto &W : Ws)
+    *jitTargetAddressToPointer<uint8_t *>(W.Address) = W.Value;
+  OnWriteComplete(Error::success());
+}
+
+void SelfTargetProcessControl::writeUInt16s(ArrayRef<tpctypes::UInt16Write> Ws,
+                                            WriteResultFn OnWriteComplete) {
+  for (auto &W : Ws)
+    *jitTargetAddressToPointer<uint16_t *>(W.Address) = W.Value;
+  OnWriteComplete(Error::success());
+}
+
+void SelfTargetProcessControl::writeUInt32s(ArrayRef<tpctypes::UInt32Write> Ws,
+                                            WriteResultFn OnWriteComplete) {
+  for (auto &W : Ws)
+    *jitTargetAddressToPointer<uint32_t *>(W.Address) = W.Value;
+  OnWriteComplete(Error::success());
+}
+
+void SelfTargetProcessControl::writeUInt64s(ArrayRef<tpctypes::UInt64Write> Ws,
+                                            WriteResultFn OnWriteComplete) {
+  for (auto &W : Ws)
+    *jitTargetAddressToPointer<uint64_t *>(W.Address) = W.Value;
+  OnWriteComplete(Error::success());
+}
+
+void SelfTargetProcessControl::writeBuffers(ArrayRef<tpctypes::BufferWrite> Ws,
+                                            WriteResultFn OnWriteComplete) {
+  for (auto &W : Ws)
+    memcpy(jitTargetAddressToPointer<char *>(W.Address), W.Buffer.data(),
+           W.Buffer.size());
+  OnWriteComplete(Error::success());
+}
+
+} // end namespace orc
+} // end namespace llvm
diff --git a/llvm/lib/ExecutionEngine/Orc/ThreadSafeModule.cpp b/llvm/lib/ExecutionEngine/Orc/ThreadSafeModule.cpp
index 1f4e6f132115..2e128dd23744 100644
--- a/llvm/lib/ExecutionEngine/Orc/ThreadSafeModule.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/ThreadSafeModule.cpp
@@ -15,7 +15,7 @@
 namespace llvm {
 namespace orc {
 
-ThreadSafeModule cloneToNewContext(ThreadSafeModule &TSM,
+ThreadSafeModule cloneToNewContext(const ThreadSafeModule &TSM,
                                    GVPredicate ShouldCloneDef,
                                    GVModifier UpdateClonedDefSource) {
   assert(TSM && "Can not clone null module");
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/RTDyldMemoryManager.cpp b/llvm/lib/ExecutionEngine/RuntimeDyld/RTDyldMemoryManager.cpp
index 46604ff4000c..b6ccd02405c1 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/RTDyldMemoryManager.cpp
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/RTDyldMemoryManager.cpp
@@ -31,16 +31,8 @@ namespace llvm {
 
 RTDyldMemoryManager::~RTDyldMemoryManager() {}
 
-// Determine whether we can register EH tables.
-#if (defined(__GNUC__) && !defined(__ARM_EABI__) && !defined(__ia64__) &&      \
-     !(defined(_AIX) && defined(__ibmxl__)) && !defined(__SEH__) &&            \
-     !defined(__USING_SJLJ_EXCEPTIONS__))
-#define HAVE_EHTABLE_SUPPORT 1
-#else
-#define HAVE_EHTABLE_SUPPORT 0
-#endif
-
-#if HAVE_EHTABLE_SUPPORT
+#if defined(HAVE_REGISTER_FRAME) && defined(HAVE_DEREGISTER_FRAME) &&          \
+    !defined(__SEH__) && !defined(__USING_SJLJ_EXCEPTIONS__)
 extern "C" void __register_frame(void *);
 extern "C" void __deregister_frame(void *);
 #else
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
index 7e9b0690ccea..e49e6e541f15 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
@@ -308,7 +308,9 @@ RuntimeDyldImpl::loadObjectImpl(const object::ObjectFile &Obj) {
                         << " SID: " << SectionID
                         << " Offset: " << format("%p", (uintptr_t)Addr)
                         << " flags: " << *FlagsOrErr << "\n");
-      GlobalSymbolTable[Name] = SymbolTableEntry(SectionID, Addr, *JITSymFlags);
+      if (!Name.empty()) // Skip absolute symbol relocations.
+        GlobalSymbolTable[Name] =
+            SymbolTableEntry(SectionID, Addr, *JITSymFlags);
     } else if (SymType == object::SymbolRef::ST_Function ||
                SymType == object::SymbolRef::ST_Data ||
                SymType == object::SymbolRef::ST_Unknown ||
@@ -340,8 +342,9 @@ RuntimeDyldImpl::loadObjectImpl(const object::ObjectFile &Obj) {
                         << " SID: " << SectionID
                         << " Offset: " << format("%p", (uintptr_t)SectOffset)
                         << " flags: " << *FlagsOrErr << "\n");
-      GlobalSymbolTable[Name] =
-          SymbolTableEntry(SectionID, SectOffset, *JITSymFlags);
+      if (!Name.empty()) // Skip absolute symbol relocations
+        GlobalSymbolTable[Name] =
+            SymbolTableEntry(SectionID, SectOffset, *JITSymFlags);
     }
   }
 
@@ -769,8 +772,9 @@ Error RuntimeDyldImpl::emitCommonSymbols(const ObjectFile &Obj,
 
     LLVM_DEBUG(dbgs() << "Allocating common symbol " << Name << " address "
                       << format("%p", Addr) << "\n");
-    GlobalSymbolTable[Name] =
-        SymbolTableEntry(SectionID, Offset, std::move(*JITSymFlags));
+    if (!Name.empty()) // Skip absolute symbol relocations.
+      GlobalSymbolTable[Name] =
+          SymbolTableEntry(SectionID, Offset, std::move(*JITSymFlags));
     Offset += Size;
     Addr += Size;
   }
@@ -930,6 +934,8 @@ void RuntimeDyldImpl::addRelocationForSymbol(const RelocationEntry &RE,
   if (Loc == GlobalSymbolTable.end()) {
     ExternalSymbolRelocations[SymbolName].push_back(RE);
   } else {
+    assert(!SymbolName.empty() &&
+           "Empty symbol should not be in GlobalSymbolTable");
     // Copy the RE since we want to modify its addend.
     RelocationEntry RECopy = RE;
     const auto &SymInfo = Loc->second;
@@ -1200,16 +1206,19 @@ Error RuntimeDyldImpl::resolveExternalSymbols() {
 
 void RuntimeDyldImpl::finalizeAsync(
     std::unique_ptr<RuntimeDyldImpl> This,
-    unique_function<void(object::OwningBinary<object::ObjectFile>, Error)>
+    unique_function<void(object::OwningBinary<object::ObjectFile>,
+                         std::unique_ptr<RuntimeDyld::LoadedObjectInfo>, Error)>
         OnEmitted,
-    object::OwningBinary<object::ObjectFile> O) {
+    object::OwningBinary<object::ObjectFile> O,
+    std::unique_ptr<RuntimeDyld::LoadedObjectInfo> Info) {
 
   auto SharedThis = std::shared_ptr<RuntimeDyldImpl>(std::move(This));
   auto PostResolveContinuation =
-      [SharedThis, OnEmitted = std::move(OnEmitted), O = std::move(O)](
+      [SharedThis, OnEmitted = std::move(OnEmitted), O = std::move(O),
+       Info = std::move(Info)](
           Expected<JITSymbolResolver::LookupResult> Result) mutable {
         if (!Result) {
-          OnEmitted(std::move(O), Result.takeError());
+          OnEmitted(std::move(O), std::move(Info), Result.takeError());
           return;
         }
 
@@ -1223,18 +1232,19 @@ void RuntimeDyldImpl::finalizeAsync(
         SharedThis->registerEHFrames();
         std::string ErrMsg;
         if (SharedThis->MemMgr.finalizeMemory(&ErrMsg))
-          OnEmitted(std::move(O),
+          OnEmitted(std::move(O), std::move(Info),
                     make_error<StringError>(std::move(ErrMsg),
                                             inconvertibleErrorCode()));
         else
-          OnEmitted(std::move(O), Error::success());
+          OnEmitted(std::move(O), std::move(Info), Error::success());
       };
 
   JITSymbolResolver::LookupSet Symbols;
 
   for (auto &RelocKV : SharedThis->ExternalSymbolRelocations) {
     StringRef Name = RelocKV.first();
-    assert(!Name.empty() && "Symbol has no name?");
+    if (Name.empty()) // Skip absolute symbol relocations.
+      continue;
     assert(!SharedThis->GlobalSymbolTable.count(Name) &&
            "Name already processed. RuntimeDyld instances can not be re-used "
            "when finalizing with finalizeAsync.");
@@ -1418,12 +1428,12 @@ void jitLinkForORC(
     object::OwningBinary<object::ObjectFile> O,
     RuntimeDyld::MemoryManager &MemMgr, JITSymbolResolver &Resolver,
     bool ProcessAllSections,
-    unique_function<
-        Error(const object::ObjectFile &Obj,
-              std::unique_ptr<RuntimeDyld::LoadedObjectInfo> LoadedObj,
-              std::map<StringRef, JITEvaluatedSymbol>)>
+    unique_function<Error(const object::ObjectFile &Obj,
+                          RuntimeDyld::LoadedObjectInfo &LoadedObj,
+                          std::map<StringRef, JITEvaluatedSymbol>)>
         OnLoaded,
-    unique_function<void(object::OwningBinary<object::ObjectFile>, Error)>
+    unique_function<void(object::OwningBinary<object::ObjectFile>,
+                         std::unique_ptr<RuntimeDyld::LoadedObjectInfo>, Error)>
         OnEmitted) {
 
   RuntimeDyld RTDyld(MemMgr, Resolver);
@@ -1432,17 +1442,17 @@ void jitLinkForORC(
   auto Info = RTDyld.loadObject(*O.getBinary());
 
   if (RTDyld.hasError()) {
-    OnEmitted(std::move(O), make_error<StringError>(RTDyld.getErrorString(),
-                                                    inconvertibleErrorCode()));
+    OnEmitted(std::move(O), std::move(Info),
+              make_error<StringError>(RTDyld.getErrorString(),
+                                      inconvertibleErrorCode()));
     return;
   }
 
-  if (auto Err =
-          OnLoaded(*O.getBinary(), std::move(Info), RTDyld.getSymbolTable()))
-    OnEmitted(std::move(O), std::move(Err));
+  if (auto Err = OnLoaded(*O.getBinary(), *Info, RTDyld.getSymbolTable()))
+    OnEmitted(std::move(O), std::move(Info), std::move(Err));
 
   RuntimeDyldImpl::finalizeAsync(std::move(RTDyld.Dyld), std::move(OnEmitted),
-                                 std::move(O));
+                                 std::move(O), std::move(Info));
 }
 
 } // end namespace llvm
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldChecker.cpp b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldChecker.cpp
index e5e512672daa..2fbe707ce8df 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldChecker.cpp
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldChecker.cpp
@@ -352,7 +352,7 @@ private:
     RemainingExpr = RemainingExpr.substr(1).ltrim();
 
     uint64_t StubAddr;
-    std::string ErrorMsg = "";
+    std::string ErrorMsg;
     std::tie(StubAddr, ErrorMsg) = Checker.getStubOrGOTAddrFor(
         StubContainerName, Symbol, PCtx.IsInsideLoad, IsStubAddr);
 
@@ -389,7 +389,7 @@ private:
     RemainingExpr = RemainingExpr.substr(1).ltrim();
 
     uint64_t StubAddr;
-    std::string ErrorMsg = "";
+    std::string ErrorMsg;
     std::tie(StubAddr, ErrorMsg) = Checker.getSectionAddr(
         FileName, SectionName, PCtx.IsInsideLoad);
 
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
index 7c39ddc8b1da..28e1faab5ac7 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
@@ -57,13 +57,6 @@ namespace {
 template <class ELFT> class DyldELFObject : public ELFObjectFile<ELFT> {
   LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
 
-  typedef Elf_Shdr_Impl<ELFT> Elf_Shdr;
-  typedef Elf_Sym_Impl<ELFT> Elf_Sym;
-  typedef Elf_Rel_Impl<ELFT, false> Elf_Rel;
-  typedef Elf_Rel_Impl<ELFT, true> Elf_Rela;
-
-  typedef Elf_Ehdr_Impl<ELFT> Elf_Ehdr;
-
   typedef typename ELFT::uint addr_type;
 
   DyldELFObject(ELFObjectFile<ELFT> &&Obj);
@@ -269,7 +262,7 @@ void RuntimeDyldELF::resolveX86_64Relocation(const SectionEntry &Section,
                                              uint64_t SymOffset) {
   switch (Type) {
   default:
-    llvm_unreachable("Relocation type not implemented yet!");
+    report_fatal_error("Relocation type not implemented yet!");
     break;
   case ELF::R_X86_64_NONE:
     break;
@@ -359,7 +352,7 @@ void RuntimeDyldELF::resolveX86Relocation(const SectionEntry &Section,
   default:
     // There are other relocation types, but it appears these are the
     // only ones currently used by the LLVM ELF object writer
-    llvm_unreachable("Relocation type not implemented yet!");
+    report_fatal_error("Relocation type not implemented yet!");
     break;
   }
 }
@@ -382,7 +375,7 @@ void RuntimeDyldELF::resolveAArch64Relocation(const SectionEntry &Section,
 
   switch (Type) {
   default:
-    llvm_unreachable("Relocation type not implemented yet!");
+    report_fatal_error("Relocation type not implemented yet!");
     break;
   case ELF::R_AARCH64_ABS16: {
     uint64_t Result = Value + Addend;
@@ -721,7 +714,7 @@ void RuntimeDyldELF::resolvePPC32Relocation(const SectionEntry &Section,
   uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
   switch (Type) {
   default:
-    llvm_unreachable("Relocation type not implemented yet!");
+    report_fatal_error("Relocation type not implemented yet!");
     break;
   case ELF::R_PPC_ADDR16_LO:
     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
@@ -741,7 +734,7 @@ void RuntimeDyldELF::resolvePPC64Relocation(const SectionEntry &Section,
   uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
   switch (Type) {
   default:
-    llvm_unreachable("Relocation type not implemented yet!");
+    report_fatal_error("Relocation type not implemented yet!");
     break;
   case ELF::R_PPC64_ADDR16:
     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
@@ -835,7 +828,7 @@ void RuntimeDyldELF::resolveSystemZRelocation(const SectionEntry &Section,
   uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
   switch (Type) {
   default:
-    llvm_unreachable("Relocation type not implemented yet!");
+    report_fatal_error("Relocation type not implemented yet!");
     break;
   case ELF::R_390_PC16DBL:
   case ELF::R_390_PLT16DBL: {
@@ -890,7 +883,7 @@ void RuntimeDyldELF::resolveBPFRelocation(const SectionEntry &Section,
 
   switch (Type) {
   default:
-    llvm_unreachable("Relocation type not implemented yet!");
+    report_fatal_error("Relocation type not implemented yet!");
     break;
   case ELF::R_BPF_NONE:
     break;
@@ -961,7 +954,8 @@ void RuntimeDyldELF::resolveRelocation(const SectionEntry &Section,
     resolveARMRelocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
                          (uint32_t)(Addend & 0xffffffffL));
     break;
-  case Triple::ppc:
+  case Triple::ppc: // Fall through.
+  case Triple::ppcle:
     resolvePPC32Relocation(Section, Offset, Value, Type, Addend);
     break;
   case Triple::ppc64: // Fall through.
@@ -1676,30 +1670,33 @@ RuntimeDyldELF::processRelocationRef(
       if (Value.SymbolName) {
         // This is a call to an external function.
         // Look for an existing stub.
-        SectionEntry &Section = Sections[SectionID];
+        SectionEntry *Section = &Sections[SectionID];
         StubMap::const_iterator i = Stubs.find(Value);
         uintptr_t StubAddress;
         if (i != Stubs.end()) {
-          StubAddress = uintptr_t(Section.getAddress()) + i->second;
+          StubAddress = uintptr_t(Section->getAddress()) + i->second;
           LLVM_DEBUG(dbgs() << " Stub function found\n");
         } else {
           // Create a new stub function (equivalent to a PLT entry).
           LLVM_DEBUG(dbgs() << " Create a new stub function\n");
 
-          uintptr_t BaseAddress = uintptr_t(Section.getAddress());
+          uintptr_t BaseAddress = uintptr_t(Section->getAddress());
           uintptr_t StubAlignment = getStubAlignment();
           StubAddress =
-              (BaseAddress + Section.getStubOffset() + StubAlignment - 1) &
+              (BaseAddress + Section->getStubOffset() + StubAlignment - 1) &
               -StubAlignment;
           unsigned StubOffset = StubAddress - BaseAddress;
           Stubs[Value] = StubOffset;
           createStubFunction((uint8_t *)StubAddress);
 
           // Bump our stub offset counter
-          Section.advanceStubOffset(getMaxStubSize());
+          Section->advanceStubOffset(getMaxStubSize());
 
           // Allocate a GOT Entry
           uint64_t GOTOffset = allocateGOTEntries(1);
+          // This potentially creates a new Section which potentially
+          // invalidates the Section pointer, so reload it.
+          Section = &Sections[SectionID];
 
           // The load of the GOT address has an addend of -4
           resolveGOTOffsetRelocation(SectionID, StubOffset + 2, GOTOffset - 4,
@@ -1712,7 +1709,7 @@ RuntimeDyldELF::processRelocationRef(
         }
 
         // Make the target call a call into the stub table.
-        resolveRelocation(Section, Offset, StubAddress, ELF::R_X86_64_PC32,
+        resolveRelocation(*Section, Offset, StubAddress, ELF::R_X86_64_PC32,
                           Addend);
       } else {
         RelocationEntry RE(SectionID, Offset, ELF::R_X86_64_PC32, Value.Addend,
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h
index a9346536fd09..d34fae9aaf0c 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h
@@ -535,9 +535,12 @@ public:
 
   static void finalizeAsync(
       std::unique_ptr<RuntimeDyldImpl> This,
-      unique_function<void(object::OwningBinary<object::ObjectFile>, Error)>
+      unique_function<void(object::OwningBinary<object::ObjectFile>,
+                           std::unique_ptr<RuntimeDyld::LoadedObjectInfo>,
+                           Error)>
           OnEmitted,
-      object::OwningBinary<object::ObjectFile> O);
+      object::OwningBinary<object::ObjectFile> O,
+      std::unique_ptr<RuntimeDyld::LoadedObjectInfo> Info);
 
   void reassignSectionAddress(unsigned SectionID, uint64_t Addr);
 
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFX86_64.h b/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFX86_64.h
index ebe3ca33d308..9df3e2e3c3bf 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFX86_64.h
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFX86_64.h
@@ -113,11 +113,10 @@ public:
       // The MemoryManager can make sure this is always true by forcing the
       // memory layout to be: CodeSection < ReadOnlySection < ReadWriteSection.
       const uint64_t ImageBase = getImageBase();
-      if (Value < ImageBase || ((Value - ImageBase) > UINT32_MAX)) {
-        llvm::errs() << "IMAGE_REL_AMD64_ADDR32NB relocation requires an"
-                     << "ordered section layout.\n";
-        write32BitOffset(Target, 0, 0);
-      } else {
+      if (Value < ImageBase || ((Value - ImageBase) > UINT32_MAX))
+        report_fatal_error("IMAGE_REL_AMD64_ADDR32NB relocation requires an "
+                           "ordered section layout");
+      else {
         write32BitOffset(Target, RE.Addend, Value - ImageBase);
       }
       break;
diff --git a/llvm/lib/ExecutionEngine/SectionMemoryManager.cpp b/llvm/lib/ExecutionEngine/SectionMemoryManager.cpp
index 925049b2a1b4..6690dd07d99b 100644
--- a/llvm/lib/ExecutionEngine/SectionMemoryManager.cpp
+++ b/llvm/lib/ExecutionEngine/SectionMemoryManager.cpp
@@ -112,6 +112,15 @@ uint8_t *SectionMemoryManager::allocateSection(
   // Save this address as the basis for our next request
   MemGroup.Near = MB;
 
+  // Copy the address to all the other groups, if they have not
+  // been initialized.
+  if (CodeMem.Near.base() == 0)
+    CodeMem.Near = MB;
+  if (RODataMem.Near.base() == 0)
+    RODataMem.Near = MB;
+  if (RWDataMem.Near.base() == 0)
+    RWDataMem.Near = MB;
+
   // Remember that we allocated this memory
   MemGroup.AllocatedMem.push_back(MB);
   Addr = (uintptr_t)MB.base();
@@ -152,8 +161,7 @@ bool SectionMemoryManager::finalizeMemory(std::string *ErrMsg) {
   }
 
   // Make read-only data memory read-only.
-  ec = applyMemoryGroupPermissions(RODataMem,
-                                   sys::Memory::MF_READ | sys::Memory::MF_EXEC);
+  ec = applyMemoryGroupPermissions(RODataMem, sys::Memory::MF_READ);
   if (ec) {
     if (ErrMsg) {
       *ErrMsg = ec.message();
@@ -210,11 +218,9 @@ SectionMemoryManager::applyMemoryGroupPermissions(MemoryGroup &MemGroup,
   }
 
   // Remove all blocks which are now empty
-  MemGroup.FreeMem.erase(remove_if(MemGroup.FreeMem,
-                                   [](FreeMemBlock &FreeMB) {
-                                     return FreeMB.Free.allocatedSize() == 0;
-                                   }),
-                         MemGroup.FreeMem.end());
+  erase_if(MemGroup.FreeMem, [](FreeMemBlock &FreeMB) {
+    return FreeMB.Free.allocatedSize() == 0;
+  });
 
   return std::error_code();
 }