diff --git a/llvm/lib/ExecutionEngine/Orc/OrcMCJITReplacement.h b/llvm/lib/ExecutionEngine/Orc/OrcMCJITReplacement.h
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+++ b/llvm/lib/ExecutionEngine/Orc/OrcMCJITReplacement.h
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+//===---- OrcMCJITReplacement.h - Orc based MCJIT replacement ---*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Orc based MCJIT replacement.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_EXECUTIONENGINE_ORC_ORCMCJITREPLACEMENT_H
+#define LLVM_LIB_EXECUTIONENGINE_ORC_ORCMCJITREPLACEMENT_H
+
+#include "llvm/ExecutionEngine/ExecutionEngine.h"
+#include "llvm/ExecutionEngine/Orc/CompileUtils.h"
+#include "llvm/ExecutionEngine/Orc/IRCompileLayer.h"
+#include "llvm/ExecutionEngine/Orc/LazyEmittingLayer.h"
+#include "llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h"
+#include "llvm/Object/Archive.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
+
+namespace llvm {
+
+class OrcMCJITReplacement : public ExecutionEngine {
+
+  class ForwardingRTDyldMM : public RTDyldMemoryManager {
+  public:
+    ForwardingRTDyldMM(OrcMCJITReplacement &M) : M(M) {}
+
+    uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
+                                 unsigned SectionID,
+                                 StringRef SectionName) override {
+      uint8_t *Addr =
+          M.MM->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 = M.MM->allocateDataSection(Size, Alignment, SectionID,
+                                                SectionName, IsReadOnly);
+      M.SectionsAllocatedSinceLastLoad.insert(Addr);
+      return Addr;
+    }
+
+    void reserveAllocationSpace(uintptr_t CodeSize, uintptr_t DataSizeRO,
+                                uintptr_t DataSizeRW) override {
+      return M.MM->reserveAllocationSpace(CodeSize, DataSizeRO, DataSizeRW);
+    }
+
+    bool needsToReserveAllocationSpace() override {
+      return M.MM->needsToReserveAllocationSpace();
+    }
+
+    void registerEHFrames(uint8_t *Addr, uint64_t LoadAddr,
+                          size_t Size) override {
+      return M.MM->registerEHFrames(Addr, LoadAddr, Size);
+    }
+
+    void deregisterEHFrames(uint8_t *Addr, uint64_t LoadAddr,
+                            size_t Size) override {
+      return M.MM->deregisterEHFrames(Addr, LoadAddr, Size);
+    }
+
+    uint64_t getSymbolAddress(const std::string &Name) override {
+      return M.getSymbolAddressWithoutMangling(Name);
+    }
+
+    void *getPointerToNamedFunction(const std::string &Name,
+                                    bool AbortOnFailure = true) override {
+      return M.MM->getPointerToNamedFunction(Name, AbortOnFailure);
+    }
+
+    void notifyObjectLoaded(ExecutionEngine *EE,
+                            const object::ObjectFile &O) override {
+      return M.MM->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 M.MM->finalizeMemory(ErrMsg);
+      return false;
+    }
+
+  private:
+    OrcMCJITReplacement &M;
+  };
+
+private:
+  static ExecutionEngine *
+  createOrcMCJITReplacement(std::string *ErrorMsg,
+                            std::unique_ptr<RTDyldMemoryManager> OrcJMM,
+                            std::unique_ptr<llvm::TargetMachine> TM) {
+    return new llvm::OrcMCJITReplacement(std::move(OrcJMM), std::move(TM));
+  }
+
+public:
+  static void Register() {
+    OrcMCJITReplacementCtor = createOrcMCJITReplacement;
+  }
+
+  OrcMCJITReplacement(std::unique_ptr<RTDyldMemoryManager> MM,
+                      std::unique_ptr<TargetMachine> TM)
+      : TM(std::move(TM)), MM(std::move(MM)),
+        Mang(this->TM->getSubtargetImpl()->getDataLayout()),
+        NotifyObjectLoaded(*this), NotifyFinalized(*this),
+        ObjectLayer(NotifyObjectLoaded, NotifyFinalized),
+        CompileLayer(ObjectLayer, SimpleCompiler(*this->TM)),
+        LazyEmitLayer(CompileLayer) {
+    setDataLayout(this->TM->getSubtargetImpl()->getDataLayout());
+  }
+
+  void addModule(std::unique_ptr<Module> M) {
+
+    // If this module doesn't have a DataLayout attached then attach the
+    // default.
+    if (!M->getDataLayout())
+      M->setDataLayout(getDataLayout());
+
+    OwnedModules.push_back(std::move(M));
+    std::vector<Module *> Ms;
+    Ms.push_back(&*OwnedModules.back());
+    LazyEmitLayer.addModuleSet(std::move(Ms),
+                               llvm::make_unique<ForwardingRTDyldMM>(*this));
+  }
+
+  void addObjectFile(std::unique_ptr<object::ObjectFile> O) override {
+    std::vector<std::unique_ptr<object::ObjectFile>> Objs;
+    Objs.push_back(std::move(O));
+    ObjectLayer.addObjectSet(std::move(Objs),
+                             llvm::make_unique<ForwardingRTDyldMM>(*this));
+  }
+
+  void addObjectFile(object::OwningBinary<object::ObjectFile> O) override {
+    std::unique_ptr<object::ObjectFile> Obj;
+    std::unique_ptr<MemoryBuffer> Buf;
+    std::tie(Obj, Buf) = O.takeBinary();
+    std::vector<std::unique_ptr<object::ObjectFile>> Objs;
+    Objs.push_back(std::move(Obj));
+    ObjectLayer.addObjectSet(std::move(Objs),
+                             llvm::make_unique<ForwardingRTDyldMM>(*this));
+  }
+
+  void addArchive(object::OwningBinary<object::Archive> A) override {
+    Archives.push_back(std::move(A));
+  }
+
+  uint64_t getSymbolAddress(StringRef Name) {
+    return getSymbolAddressWithoutMangling(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,
+                           const std::vector<GenericValue> &ArgValues) override;
+
+  void setObjectCache(ObjectCache *NewCache) override {
+    CompileLayer.setObjectCache(NewCache);
+  }
+
+private:
+  uint64_t getSymbolAddressWithoutMangling(StringRef Name) {
+    if (uint64_t Addr = LazyEmitLayer.getSymbolAddress(Name, false))
+      return Addr;
+    if (uint64_t Addr = MM->getSymbolAddress(Name))
+      return Addr;
+    if (uint64_t Addr = scanArchives(Name))
+      return Addr;
+
+    return 0;
+  }
+
+  uint64_t scanArchives(StringRef Name) {
+    for (object::OwningBinary<object::Archive> &OB : Archives) {
+      object::Archive *A = OB.getBinary();
+      // Look for our symbols in each Archive
+      object::Archive::child_iterator ChildIt = A->findSym(Name);
+      if (ChildIt != A->child_end()) {
+        // FIXME: Support nested archives?
+        ErrorOr<std::unique_ptr<object::Binary>> ChildBinOrErr =
+            ChildIt->getAsBinary();
+        if (ChildBinOrErr.getError())
+          continue;
+        std::unique_ptr<object::Binary> &ChildBin = ChildBinOrErr.get();
+        if (ChildBin->isObject()) {
+          std::vector<std::unique_ptr<object::ObjectFile>> ObjSet;
+          ObjSet.push_back(std::unique_ptr<object::ObjectFile>(
+              static_cast<object::ObjectFile *>(ChildBin.release())));
+          ObjectLayer.addObjectSet(
+              std::move(ObjSet), llvm::make_unique<ForwardingRTDyldMM>(*this));
+          if (uint64_t Addr = ObjectLayer.getSymbolAddress(Name, true))
+            return Addr;
+        }
+      }
+    }
+    return 0;
+  }
+
+  class NotifyObjectLoadedT {
+  public:
+    typedef std::vector<std::unique_ptr<object::ObjectFile>> ObjListT;
+    typedef std::vector<std::unique_ptr<RuntimeDyld::LoadedObjectInfo>>
+        LoadedObjInfoListT;
+
+    NotifyObjectLoadedT(OrcMCJITReplacement &M) : M(M) {}
+
+    void operator()(ObjectLinkingLayerBase::ObjSetHandleT H,
+                    const ObjListT &Objects,
+                    const LoadedObjInfoListT &Infos) const {
+      M.UnfinalizedSections[H] = std::move(M.SectionsAllocatedSinceLastLoad);
+      M.SectionsAllocatedSinceLastLoad = {};
+      assert(Objects.size() == Infos.size() &&
+             "Incorrect number of Infos for Objects.");
+      for (unsigned I = 0; I < Objects.size(); ++I)
+        M.MM->notifyObjectLoaded(&M, *Objects[I]);
+    };
+
+  private:
+    OrcMCJITReplacement &M;
+  };
+
+  class NotifyFinalizedT {
+  public:
+    NotifyFinalizedT(OrcMCJITReplacement &M) : M(M) {}
+    void operator()(ObjectLinkingLayerBase::ObjSetHandleT H) {
+      M.UnfinalizedSections.erase(H);
+    }
+
+  private:
+    OrcMCJITReplacement &M;
+  };
+
+  std::string Mangle(StringRef Name) {
+    std::string MangledName;
+    {
+      raw_string_ostream MangledNameStream(MangledName);
+      Mang.getNameWithPrefix(MangledNameStream, Name);
+    }
+    return MangledName;
+  }
+
+  typedef ObjectLinkingLayer<NotifyObjectLoadedT> ObjectLayerT;
+  typedef IRCompileLayer<ObjectLayerT> CompileLayerT;
+  typedef LazyEmittingLayer<CompileLayerT> LazyEmitLayerT;
+
+  std::unique_ptr<TargetMachine> TM;
+  std::unique_ptr<RTDyldMemoryManager> MM;
+  Mangler Mang;
+
+  NotifyObjectLoadedT NotifyObjectLoaded;
+  NotifyFinalizedT NotifyFinalized;
+
+  ObjectLayerT ObjectLayer;
+  CompileLayerT CompileLayer;
+  LazyEmitLayerT LazyEmitLayer;
+
+  // MCJIT keeps modules alive - we need to do the same for backwards
+  // compatibility.
+  std::vector<std::unique_ptr<Module>> OwnedModules;
+
+  // 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.
+  typedef std::set<const void *> SectionAddrSet;
+  struct ObjSetHandleCompare {
+    bool operator()(ObjectLayerT::ObjSetHandleT H1,
+                    ObjectLayerT::ObjSetHandleT H2) const {
+      return &*H1 < &*H2;
+    }
+  };
+  SectionAddrSet SectionsAllocatedSinceLastLoad;
+  std::map<ObjectLayerT::ObjSetHandleT, SectionAddrSet, ObjSetHandleCompare>
+      UnfinalizedSections;
+
+  std::vector<object::OwningBinary<object::Archive>> Archives;
+};
+}
+
+#endif // LLVM_LIB_EXECUTIONENGINE_ORC_MCJITREPLACEMENT_H