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diff --git a/include/llvm/Analysis/LazyBlockFrequencyInfo.h b/include/llvm/Analysis/LazyBlockFrequencyInfo.h
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+++ b/include/llvm/Analysis/LazyBlockFrequencyInfo.h
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+//===- LazyBlockFrequencyInfo.h - Lazy Block Frequency Analysis -*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This is an alternative analysis pass to BlockFrequencyInfoWrapperPass.  The
+// difference is that with this pass the block frequencies are not computed when
+// the analysis pass is executed but rather when the BFI results is explicitly
+// requested by the analysis client.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_LAZYBLOCKFREQUENCYINFO_H
+#define LLVM_ANALYSIS_LAZYBLOCKFREQUENCYINFO_H
+
+#include "llvm/Analysis/BlockFrequencyInfo.h"
+#include "llvm/Pass.h"
+
+namespace llvm {
+class AnalysisUsage;
+class BranchProbabilityInfo;
+class Function;
+class LoopInfo;
+
+/// \brief This is an alternative analysis pass to
+/// BlockFrequencyInfoWrapperPass.  The difference is that with this pass the
+/// block frequencies are not computed when the analysis pass is executed but
+/// rather when the BFI results is explicitly requested by the analysis client.
+///
+/// There are some additional requirements for any client pass that wants to use
+/// the analysis:
+///
+/// 1. The pass needs to initialize dependent passes with:
+///
+///   INITIALIZE_PASS_DEPENDENCY(LazyBFIPass)
+///
+/// 2. Similarly, getAnalysisUsage should call:
+///
+///   LazyBlockFrequencyInfoPass::getLazyBFIAnalysisUsage(AU)
+///
+/// 3. The computed BFI should be requested with
+///    getAnalysis<LazyBlockFrequencyInfoPass>().getBFI() before either LoopInfo
+///    or BPI could be invalidated for example by changing the CFG.
+///
+/// Note that it is expected that we wouldn't need this functionality for the
+/// new PM since with the new PM, analyses are executed on demand.
+class LazyBlockFrequencyInfoPass : public FunctionPass {
+
+  /// Wraps a BFI to allow lazy computation of the block frequencies.
+  ///
+  /// A pass that only conditionally uses BFI can uncondtionally require the
+  /// analysis without paying for the overhead if BFI doesn't end up being used.
+  class LazyBlockFrequencyInfo {
+  public:
+    LazyBlockFrequencyInfo()
+        : Calculated(false), F(nullptr), BPI(nullptr), LI(nullptr) {}
+
+    /// Set up the per-function input.
+    void setAnalysis(const Function *F, const BranchProbabilityInfo *BPI,
+                     const LoopInfo *LI) {
+      this->F = F;
+      this->BPI = BPI;
+      this->LI = LI;
+    }
+
+    /// Retrieve the BFI with the block frequencies computed.
+    BlockFrequencyInfo &getCalculated() {
+      if (!Calculated) {
+        assert(F && BPI && LI && "call setAnalysis");
+        BFI.calculate(*F, *BPI, *LI);
+        Calculated = true;
+      }
+      return BFI;
+    }
+
+    const BlockFrequencyInfo &getCalculated() const {
+      return const_cast<LazyBlockFrequencyInfo *>(this)->getCalculated();
+    }
+
+    void releaseMemory() {
+      BFI.releaseMemory();
+      Calculated = false;
+      setAnalysis(nullptr, nullptr, nullptr);
+    }
+
+  private:
+    BlockFrequencyInfo BFI;
+    bool Calculated;
+    const Function *F;
+    const BranchProbabilityInfo *BPI;
+    const LoopInfo *LI;
+  };
+
+  LazyBlockFrequencyInfo LBFI;
+
+public:
+  static char ID;
+
+  LazyBlockFrequencyInfoPass();
+
+  /// \brief Compute and return the block frequencies.
+  BlockFrequencyInfo &getBFI() { return LBFI.getCalculated(); }
+
+  /// \brief Compute and return the block frequencies.
+  const BlockFrequencyInfo &getBFI() const { return LBFI.getCalculated(); }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override;
+
+  /// Helper for client passes to set up the analysis usage on behalf of this
+  /// pass.
+  static void getLazyBFIAnalysisUsage(AnalysisUsage &AU);
+
+  bool runOnFunction(Function &F) override;
+  void releaseMemory() override;
+  void print(raw_ostream &OS, const Module *M) const override;
+};
+
+/// \brief Helper for client passes to initialize dependent passes for LBFI.
+void initializeLazyBFIPassPass(PassRegistry &Registry);
+}
+#endif