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diff --git a/tools/clang-fuzzer/handle-llvm/handle_llvm.cpp b/tools/clang-fuzzer/handle-llvm/handle_llvm.cpp
new file mode 100644
index 0000000000000..ef544ae711aba
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+++ b/tools/clang-fuzzer/handle-llvm/handle_llvm.cpp
@@ -0,0 +1,178 @@
+//==-- handle_llvm.cpp - Helper function for Clang fuzzers -----------------==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Implements HandleLLVM for use by the Clang fuzzers. First runs a loop
+// vectorizer optimization pass over the given IR code. Then mimics lli on both
+// versions to JIT the generated code and execute it. Currently, functions are 
+// executed on dummy inputs.
+//
+//===----------------------------------------------------------------------===//
+
+#include "handle_llvm.h"
+
+#include "llvm/ADT/Triple.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/CodeGen/CommandFlags.inc"
+#include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/CodeGen/TargetPassConfig.h"
+#include "llvm/ExecutionEngine/JITEventListener.h"
+#include "llvm/ExecutionEngine/JITSymbol.h"
+#include "llvm/ExecutionEngine/MCJIT.h"
+#include "llvm/ExecutionEngine/ObjectCache.h"
+#include "llvm/ExecutionEngine/RTDyldMemoryManager.h"
+#include "llvm/ExecutionEngine/SectionMemoryManager.h"
+#include "llvm/IR/IRPrintingPasses.h"
+#include "llvm/IR/LegacyPassManager.h"
+#include "llvm/IR/LegacyPassNameParser.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/Verifier.h"
+#include "llvm/IRReader/IRReader.h"
+#include "llvm/Pass.h"
+#include "llvm/PassRegistry.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/SourceMgr.h"
+#include "llvm/Support/TargetRegistry.h"
+#include "llvm/Support/TargetSelect.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Transforms/IPO/PassManagerBuilder.h"
+#include "llvm/Transforms/IPO.h"
+#include "llvm/Transforms/Vectorize.h"
+
+using namespace llvm;
+
+// Helper function to parse command line args and find the optimization level
+static void getOptLevel(const std::vector<const char *> &ExtraArgs,
+                              CodeGenOpt::Level &OLvl) {
+  // Find the optimization level from the command line args
+  OLvl = CodeGenOpt::Default;
+  for (auto &A : ExtraArgs) {
+    if (A[0] == '-' && A[1] == 'O') {
+      switch(A[2]) {
+        case '0': OLvl = CodeGenOpt::None; break;
+        case '1': OLvl = CodeGenOpt::Less; break;
+        case '2': OLvl = CodeGenOpt::Default; break;
+        case '3': OLvl = CodeGenOpt::Aggressive; break;
+        default:
+          errs() << "error: opt level must be between 0 and 3.\n";
+          std::exit(1);
+      }
+    }
+  }
+}
+
+void ErrorAndExit(std::string message) {
+  errs()<< "ERROR: " << message << "\n";
+  std::exit(1);
+}
+
+// Helper function to add optimization passes to the TargetMachine at the 
+// specified optimization level, OptLevel
+static void AddOptimizationPasses(legacy::PassManagerBase &MPM,
+                                  CodeGenOpt::Level OptLevel,
+                                  unsigned SizeLevel) {
+  // Create and initialize a PassManagerBuilder
+  PassManagerBuilder Builder;
+  Builder.OptLevel = OptLevel;
+  Builder.SizeLevel = SizeLevel;
+  Builder.Inliner = createFunctionInliningPass(OptLevel, SizeLevel, false);
+  Builder.LoopVectorize = true;
+  Builder.populateModulePassManager(MPM);
+}
+
+// Mimics the opt tool to run an optimization pass over the provided IR
+std::string OptLLVM(const std::string &IR, CodeGenOpt::Level OLvl) {
+  // Create a module that will run the optimization passes
+  SMDiagnostic Err;
+  LLVMContext Context;
+  std::unique_ptr<Module> M = parseIR(MemoryBufferRef(IR, "IR"), Err, Context);
+  if (!M || verifyModule(*M, &errs()))
+    ErrorAndExit("Could not parse IR");
+
+  setFunctionAttributes(getCPUStr(), getFeaturesStr(), *M);
+  
+  legacy::PassManager Passes;
+  Triple ModuleTriple(M->getTargetTriple());
+  
+  Passes.add(new TargetLibraryInfoWrapperPass(ModuleTriple));
+  Passes.add(createTargetTransformInfoWrapperPass(TargetIRAnalysis()));
+  Passes.add(createVerifierPass());
+
+  AddOptimizationPasses(Passes, OLvl, 0);
+  
+  // Add a pass that writes the optimized IR to an output stream
+  std::string outString;
+  raw_string_ostream OS(outString);
+  Passes.add(createPrintModulePass(OS, "", false));
+
+  Passes.run(*M);
+
+  return OS.str();
+}
+
+void CreateAndRunJITFun(const std::string &IR, CodeGenOpt::Level OLvl) {
+  SMDiagnostic Err;
+  LLVMContext Context;
+  std::unique_ptr<Module> M = parseIR(MemoryBufferRef(IR, "IR"), Err,
+                                          Context);
+  if (!M)
+    ErrorAndExit("Could not parse IR");
+
+  Function *EntryFunc = M->getFunction("foo");
+  if (!EntryFunc)
+    ErrorAndExit("Function not found in module");
+
+  std::string ErrorMsg;
+  EngineBuilder builder(std::move(M));
+  builder.setMArch(MArch);
+  builder.setMCPU(getCPUStr());
+  builder.setMAttrs(getFeatureList());
+  builder.setErrorStr(&ErrorMsg);
+  builder.setEngineKind(EngineKind::JIT);
+  builder.setUseOrcMCJITReplacement(false);
+  builder.setMCJITMemoryManager(make_unique<SectionMemoryManager>());
+  builder.setOptLevel(OLvl);
+  builder.setTargetOptions(InitTargetOptionsFromCodeGenFlags());
+
+  std::unique_ptr<ExecutionEngine> EE(builder.create());
+  if (!EE)
+    ErrorAndExit("Could not create execution engine");
+
+  EE->finalizeObject();
+  EE->runStaticConstructorsDestructors(false);
+
+  typedef void (*func)(int*, int*, int*, int);
+  func f = reinterpret_cast<func>(EE->getPointerToFunction(EntryFunc)); 
+
+  // Define some dummy arrays to use an input for now
+  int a[] = {1};
+  int b[] = {1};
+  int c[] = {1};
+  f(a, b, c, 1);
+
+  EE->runStaticConstructorsDestructors(true);
+}
+
+// Main fuzz target called by ExampleClangLLVMProtoFuzzer.cpp
+// Mimics the lli tool to JIT the LLVM IR code and execute it
+void clang_fuzzer::HandleLLVM(const std::string &IR,
+                              const std::vector<const char *> &ExtraArgs) {
+  // Parse ExtraArgs to set the optimization level
+  CodeGenOpt::Level OLvl;
+  getOptLevel(ExtraArgs, OLvl);
+
+  // First we optimize the IR by running a loop vectorizer pass
+  std::string OptIR = OptLLVM(IR, OLvl);
+
+  CreateAndRunJITFun(OptIR, OLvl);
+  CreateAndRunJITFun(IR, CodeGenOpt::None);
+  
+  return;
+}