diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp
new file mode 100644
index 0000000..623e9b2
--- /dev/null
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp
@@ -0,0 +1,524 @@
+//===-- RuntimeDyldMachO.cpp - Run-time dynamic linker for MC-JIT ------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Implementation of the MC-JIT runtime dynamic linker.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "dyld"
+#include "llvm/ADT/OwningPtr.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/STLExtras.h"
+#include "RuntimeDyldImpl.h"
+using namespace llvm;
+using namespace llvm::object;
+
+namespace llvm {
+
+bool RuntimeDyldMachO::
+resolveRelocation(uint8_t *Address, uint8_t *Value, bool isPCRel,
+                  unsigned Type, unsigned Size) {
+  // This just dispatches to the proper target specific routine.
+  switch (CPUType) {
+  default: assert(0 && "Unsupported CPU type!");
+  case mach::CTM_x86_64:
+    return resolveX86_64Relocation((uintptr_t)Address, (uintptr_t)Value,
+                                   isPCRel, Type, Size);
+  case mach::CTM_ARM:
+    return resolveARMRelocation((uintptr_t)Address, (uintptr_t)Value,
+                                isPCRel, Type, Size);
+  }
+  llvm_unreachable("");
+}
+
+bool RuntimeDyldMachO::
+resolveX86_64Relocation(uintptr_t Address, uintptr_t Value,
+                        bool isPCRel, unsigned Type,
+                        unsigned Size) {
+  // If the relocation is PC-relative, the value to be encoded is the
+  // pointer difference.
+  if (isPCRel)
+    // FIXME: It seems this value needs to be adjusted by 4 for an effective PC
+    // address. Is that expected? Only for branches, perhaps?
+    Value -= Address + 4;
+
+  switch(Type) {
+  default:
+    llvm_unreachable("Invalid relocation type!");
+  case macho::RIT_X86_64_Unsigned:
+  case macho::RIT_X86_64_Branch: {
+    // Mask in the target value a byte at a time (we don't have an alignment
+    // guarantee for the target address, so this is safest).
+    uint8_t *p = (uint8_t*)Address;
+    for (unsigned i = 0; i < Size; ++i) {
+      *p++ = (uint8_t)Value;
+      Value >>= 8;
+    }
+    return false;
+  }
+  case macho::RIT_X86_64_Signed:
+  case macho::RIT_X86_64_GOTLoad:
+  case macho::RIT_X86_64_GOT:
+  case macho::RIT_X86_64_Subtractor:
+  case macho::RIT_X86_64_Signed1:
+  case macho::RIT_X86_64_Signed2:
+  case macho::RIT_X86_64_Signed4:
+  case macho::RIT_X86_64_TLV:
+    return Error("Relocation type not implemented yet!");
+  }
+  return false;
+}
+
+bool RuntimeDyldMachO::resolveARMRelocation(uintptr_t Address, uintptr_t Value,
+                                         bool isPCRel, unsigned Type,
+                                         unsigned Size) {
+  // If the relocation is PC-relative, the value to be encoded is the
+  // pointer difference.
+  if (isPCRel) {
+    Value -= Address;
+    // ARM PCRel relocations have an effective-PC offset of two instructions
+    // (four bytes in Thumb mode, 8 bytes in ARM mode).
+    // FIXME: For now, assume ARM mode.
+    Value -= 8;
+  }
+
+  switch(Type) {
+  default:
+    llvm_unreachable("Invalid relocation type!");
+  case macho::RIT_Vanilla: {
+    llvm_unreachable("Invalid relocation type!");
+    // Mask in the target value a byte at a time (we don't have an alignment
+    // guarantee for the target address, so this is safest).
+    uint8_t *p = (uint8_t*)Address;
+    for (unsigned i = 0; i < Size; ++i) {
+      *p++ = (uint8_t)Value;
+      Value >>= 8;
+    }
+    break;
+  }
+  case macho::RIT_ARM_Branch24Bit: {
+    // Mask the value into the target address. We know instructions are
+    // 32-bit aligned, so we can do it all at once.
+    uint32_t *p = (uint32_t*)Address;
+    // The low two bits of the value are not encoded.
+    Value >>= 2;
+    // Mask the value to 24 bits.
+    Value &= 0xffffff;
+    // FIXME: If the destination is a Thumb function (and the instruction
+    // is a non-predicated BL instruction), we need to change it to a BLX
+    // instruction instead.
+
+    // Insert the value into the instruction.
+    *p = (*p & ~0xffffff) | Value;
+    break;
+  }
+  case macho::RIT_ARM_ThumbBranch22Bit:
+  case macho::RIT_ARM_ThumbBranch32Bit:
+  case macho::RIT_ARM_Half:
+  case macho::RIT_ARM_HalfDifference:
+  case macho::RIT_Pair:
+  case macho::RIT_Difference:
+  case macho::RIT_ARM_LocalDifference:
+  case macho::RIT_ARM_PreboundLazyPointer:
+    return Error("Relocation type not implemented yet!");
+  }
+  return false;
+}
+
+bool RuntimeDyldMachO::
+loadSegment32(const MachOObject *Obj,
+              const MachOObject::LoadCommandInfo *SegmentLCI,
+              const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) {
+  InMemoryStruct<macho::SegmentLoadCommand> SegmentLC;
+  Obj->ReadSegmentLoadCommand(*SegmentLCI, SegmentLC);
+  if (!SegmentLC)
+    return Error("unable to load segment load command");
+
+  for (unsigned SectNum = 0; SectNum != SegmentLC->NumSections; ++SectNum) {
+    InMemoryStruct<macho::Section> Sect;
+    Obj->ReadSection(*SegmentLCI, SectNum, Sect);
+    if (!Sect)
+      return Error("unable to load section: '" + Twine(SectNum) + "'");
+
+    // FIXME: For the time being, we're only loading text segments.
+    if (Sect->Flags != 0x80000400)
+      continue;
+
+    // Address and names of symbols in the section.
+    typedef std::pair<uint64_t, StringRef> SymbolEntry;
+    SmallVector<SymbolEntry, 64> Symbols;
+    // Index of all the names, in this section or not. Used when we're
+    // dealing with relocation entries.
+    SmallVector<StringRef, 64> SymbolNames;
+    for (unsigned i = 0; i != SymtabLC->NumSymbolTableEntries; ++i) {
+      InMemoryStruct<macho::SymbolTableEntry> STE;
+      Obj->ReadSymbolTableEntry(SymtabLC->SymbolTableOffset, i, STE);
+      if (!STE)
+        return Error("unable to read symbol: '" + Twine(i) + "'");
+      if (STE->SectionIndex > SegmentLC->NumSections)
+        return Error("invalid section index for symbol: '" + Twine(i) + "'");
+      // Get the symbol name.
+      StringRef Name = Obj->getStringAtIndex(STE->StringIndex);
+      SymbolNames.push_back(Name);
+
+      // Just skip symbols not defined in this section.
+      if ((unsigned)STE->SectionIndex - 1 != SectNum)
+        continue;
+
+      // FIXME: Check the symbol type and flags.
+      if (STE->Type != 0xF)  // external, defined in this section.
+        continue;
+      // Flags == 0x8 marks a thumb function for ARM, which is fine as it
+      // doesn't require any special handling here.
+      if (STE->Flags != 0x0 && STE->Flags != 0x8)
+        continue;
+
+      // Remember the symbol.
+      Symbols.push_back(SymbolEntry(STE->Value, Name));
+
+      DEBUG(dbgs() << "Function sym: '" << Name << "' @ " <<
+            (Sect->Address + STE->Value) << "\n");
+    }
+    // Sort the symbols by address, just in case they didn't come in that way.
+    array_pod_sort(Symbols.begin(), Symbols.end());
+
+    // If there weren't any functions (odd, but just in case...)
+    if (!Symbols.size())
+      continue;
+
+    // Extract the function data.
+    uint8_t *Base = (uint8_t*)Obj->getData(SegmentLC->FileOffset,
+                                           SegmentLC->FileSize).data();
+    for (unsigned i = 0, e = Symbols.size() - 1; i != e; ++i) {
+      uint64_t StartOffset = Sect->Address + Symbols[i].first;
+      uint64_t EndOffset = Symbols[i + 1].first - 1;
+      DEBUG(dbgs() << "Extracting function: " << Symbols[i].second
+                   << " from [" << StartOffset << ", " << EndOffset << "]\n");
+      extractFunction(Symbols[i].second, Base + StartOffset, Base + EndOffset);
+    }
+    // The last symbol we do after since the end address is calculated
+    // differently because there is no next symbol to reference.
+    uint64_t StartOffset = Symbols[Symbols.size() - 1].first;
+    uint64_t EndOffset = Sect->Size - 1;
+    DEBUG(dbgs() << "Extracting function: " << Symbols[Symbols.size()-1].second
+                 << " from [" << StartOffset << ", " << EndOffset << "]\n");
+    extractFunction(Symbols[Symbols.size()-1].second,
+                    Base + StartOffset, Base + EndOffset);
+
+    // Now extract the relocation information for each function and process it.
+    for (unsigned j = 0; j != Sect->NumRelocationTableEntries; ++j) {
+      InMemoryStruct<macho::RelocationEntry> RE;
+      Obj->ReadRelocationEntry(Sect->RelocationTableOffset, j, RE);
+      if (RE->Word0 & macho::RF_Scattered)
+        return Error("NOT YET IMPLEMENTED: scattered relocations.");
+      // Word0 of the relocation is the offset into the section where the
+      // relocation should be applied. We need to translate that into an
+      // offset into a function since that's our atom.
+      uint32_t Offset = RE->Word0;
+      // Look for the function containing the address. This is used for JIT
+      // code, so the number of functions in section is almost always going
+      // to be very small (usually just one), so until we have use cases
+      // where that's not true, just use a trivial linear search.
+      unsigned SymbolNum;
+      unsigned NumSymbols = Symbols.size();
+      assert(NumSymbols > 0 && Symbols[0].first <= Offset &&
+             "No symbol containing relocation!");
+      for (SymbolNum = 0; SymbolNum < NumSymbols - 1; ++SymbolNum)
+        if (Symbols[SymbolNum + 1].first > Offset)
+          break;
+      // Adjust the offset to be relative to the symbol.
+      Offset -= Symbols[SymbolNum].first;
+      // Get the name of the symbol containing the relocation.
+      StringRef TargetName = SymbolNames[SymbolNum];
+
+      bool isExtern = (RE->Word1 >> 27) & 1;
+      // Figure out the source symbol of the relocation. If isExtern is true,
+      // this relocation references the symbol table, otherwise it references
+      // a section in the same object, numbered from 1 through NumSections
+      // (SectionBases is [0, NumSections-1]).
+      // FIXME: Some targets (ARM) use internal relocations even for
+      // externally visible symbols, if the definition is in the same
+      // file as the reference. We need to convert those back to by-name
+      // references. We can resolve the address based on the section
+      // offset and see if we have a symbol at that address. If we do,
+      // use that; otherwise, puke.
+      if (!isExtern)
+        return Error("Internal relocations not supported.");
+      uint32_t SourceNum = RE->Word1 & 0xffffff; // 24-bit value
+      StringRef SourceName = SymbolNames[SourceNum];
+
+      // FIXME: Get the relocation addend from the target address.
+
+      // Now store the relocation information. Associate it with the source
+      // symbol.
+      Relocations[SourceName].push_back(RelocationEntry(TargetName,
+                                                        Offset,
+                                                        RE->Word1,
+                                                        0 /*Addend*/));
+      DEBUG(dbgs() << "Relocation at '" << TargetName << "' + " << Offset
+                   << " from '" << SourceName << "(Word1: "
+                   << format("0x%x", RE->Word1) << ")\n");
+    }
+  }
+  return false;
+}
+
+
+bool RuntimeDyldMachO::
+loadSegment64(const MachOObject *Obj,
+              const MachOObject::LoadCommandInfo *SegmentLCI,
+              const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) {
+  InMemoryStruct<macho::Segment64LoadCommand> Segment64LC;
+  Obj->ReadSegment64LoadCommand(*SegmentLCI, Segment64LC);
+  if (!Segment64LC)
+    return Error("unable to load segment load command");
+
+  for (unsigned SectNum = 0; SectNum != Segment64LC->NumSections; ++SectNum) {
+    InMemoryStruct<macho::Section64> Sect;
+    Obj->ReadSection64(*SegmentLCI, SectNum, Sect);
+    if (!Sect)
+      return Error("unable to load section: '" + Twine(SectNum) + "'");
+
+    // FIXME: For the time being, we're only loading text segments.
+    if (Sect->Flags != 0x80000400)
+      continue;
+
+    // Address and names of symbols in the section.
+    typedef std::pair<uint64_t, StringRef> SymbolEntry;
+    SmallVector<SymbolEntry, 64> Symbols;
+    // Index of all the names, in this section or not. Used when we're
+    // dealing with relocation entries.
+    SmallVector<StringRef, 64> SymbolNames;
+    for (unsigned i = 0; i != SymtabLC->NumSymbolTableEntries; ++i) {
+      InMemoryStruct<macho::Symbol64TableEntry> STE;
+      Obj->ReadSymbol64TableEntry(SymtabLC->SymbolTableOffset, i, STE);
+      if (!STE)
+        return Error("unable to read symbol: '" + Twine(i) + "'");
+      if (STE->SectionIndex > Segment64LC->NumSections)
+        return Error("invalid section index for symbol: '" + Twine(i) + "'");
+      // Get the symbol name.
+      StringRef Name = Obj->getStringAtIndex(STE->StringIndex);
+      SymbolNames.push_back(Name);
+
+      // Just skip symbols not defined in this section.
+      if ((unsigned)STE->SectionIndex - 1 != SectNum)
+        continue;
+
+      // FIXME: Check the symbol type and flags.
+      if (STE->Type != 0xF)  // external, defined in this section.
+        continue;
+      if (STE->Flags != 0x0)
+        continue;
+
+      // Remember the symbol.
+      Symbols.push_back(SymbolEntry(STE->Value, Name));
+
+      DEBUG(dbgs() << "Function sym: '" << Name << "' @ " <<
+            (Sect->Address + STE->Value) << "\n");
+    }
+    // Sort the symbols by address, just in case they didn't come in that way.
+    array_pod_sort(Symbols.begin(), Symbols.end());
+
+    // If there weren't any functions (odd, but just in case...)
+    if (!Symbols.size())
+      continue;
+
+    // Extract the function data.
+    uint8_t *Base = (uint8_t*)Obj->getData(Segment64LC->FileOffset,
+                                           Segment64LC->FileSize).data();
+    for (unsigned i = 0, e = Symbols.size() - 1; i != e; ++i) {
+      uint64_t StartOffset = Sect->Address + Symbols[i].first;
+      uint64_t EndOffset = Symbols[i + 1].first - 1;
+      DEBUG(dbgs() << "Extracting function: " << Symbols[i].second
+                   << " from [" << StartOffset << ", " << EndOffset << "]\n");
+      extractFunction(Symbols[i].second, Base + StartOffset, Base + EndOffset);
+    }
+    // The last symbol we do after since the end address is calculated
+    // differently because there is no next symbol to reference.
+    uint64_t StartOffset = Symbols[Symbols.size() - 1].first;
+    uint64_t EndOffset = Sect->Size - 1;
+    DEBUG(dbgs() << "Extracting function: " << Symbols[Symbols.size()-1].second
+                 << " from [" << StartOffset << ", " << EndOffset << "]\n");
+    extractFunction(Symbols[Symbols.size()-1].second,
+                    Base + StartOffset, Base + EndOffset);
+
+    // Now extract the relocation information for each function and process it.
+    for (unsigned j = 0; j != Sect->NumRelocationTableEntries; ++j) {
+      InMemoryStruct<macho::RelocationEntry> RE;
+      Obj->ReadRelocationEntry(Sect->RelocationTableOffset, j, RE);
+      if (RE->Word0 & macho::RF_Scattered)
+        return Error("NOT YET IMPLEMENTED: scattered relocations.");
+      // Word0 of the relocation is the offset into the section where the
+      // relocation should be applied. We need to translate that into an
+      // offset into a function since that's our atom.
+      uint32_t Offset = RE->Word0;
+      // Look for the function containing the address. This is used for JIT
+      // code, so the number of functions in section is almost always going
+      // to be very small (usually just one), so until we have use cases
+      // where that's not true, just use a trivial linear search.
+      unsigned SymbolNum;
+      unsigned NumSymbols = Symbols.size();
+      assert(NumSymbols > 0 && Symbols[0].first <= Offset &&
+             "No symbol containing relocation!");
+      for (SymbolNum = 0; SymbolNum < NumSymbols - 1; ++SymbolNum)
+        if (Symbols[SymbolNum + 1].first > Offset)
+          break;
+      // Adjust the offset to be relative to the symbol.
+      Offset -= Symbols[SymbolNum].first;
+      // Get the name of the symbol containing the relocation.
+      StringRef TargetName = SymbolNames[SymbolNum];
+
+      bool isExtern = (RE->Word1 >> 27) & 1;
+      // Figure out the source symbol of the relocation. If isExtern is true,
+      // this relocation references the symbol table, otherwise it references
+      // a section in the same object, numbered from 1 through NumSections
+      // (SectionBases is [0, NumSections-1]).
+      if (!isExtern)
+        return Error("Internal relocations not supported.");
+      uint32_t SourceNum = RE->Word1 & 0xffffff; // 24-bit value
+      StringRef SourceName = SymbolNames[SourceNum];
+
+      // FIXME: Get the relocation addend from the target address.
+
+      // Now store the relocation information. Associate it with the source
+      // symbol.
+      Relocations[SourceName].push_back(RelocationEntry(TargetName,
+                                                        Offset,
+                                                        RE->Word1,
+                                                        0 /*Addend*/));
+      DEBUG(dbgs() << "Relocation at '" << TargetName << "' + " << Offset
+                   << " from '" << SourceName << "(Word1: "
+                   << format("0x%x", RE->Word1) << ")\n");
+    }
+  }
+  return false;
+}
+
+bool RuntimeDyldMachO::loadObject(MemoryBuffer *InputBuffer) {
+  // If the linker is in an error state, don't do anything.
+  if (hasError())
+    return true;
+  // Load the Mach-O wrapper object.
+  std::string ErrorStr;
+  OwningPtr<MachOObject> Obj(
+    MachOObject::LoadFromBuffer(InputBuffer, &ErrorStr));
+  if (!Obj)
+    return Error("unable to load object: '" + ErrorStr + "'");
+
+  // Get the CPU type information from the header.
+  const macho::Header &Header = Obj->getHeader();
+
+  // FIXME: Error checking that the loaded object is compatible with
+  //        the system we're running on.
+  CPUType = Header.CPUType;
+  CPUSubtype = Header.CPUSubtype;
+
+  // Validate that the load commands match what we expect.
+  const MachOObject::LoadCommandInfo *SegmentLCI = 0, *SymtabLCI = 0,
+    *DysymtabLCI = 0;
+  for (unsigned i = 0; i != Header.NumLoadCommands; ++i) {
+    const MachOObject::LoadCommandInfo &LCI = Obj->getLoadCommandInfo(i);
+    switch (LCI.Command.Type) {
+    case macho::LCT_Segment:
+    case macho::LCT_Segment64:
+      if (SegmentLCI)
+        return Error("unexpected input object (multiple segments)");
+      SegmentLCI = &LCI;
+      break;
+    case macho::LCT_Symtab:
+      if (SymtabLCI)
+        return Error("unexpected input object (multiple symbol tables)");
+      SymtabLCI = &LCI;
+      break;
+    case macho::LCT_Dysymtab:
+      if (DysymtabLCI)
+        return Error("unexpected input object (multiple symbol tables)");
+      DysymtabLCI = &LCI;
+      break;
+    default:
+      return Error("unexpected input object (unexpected load command");
+    }
+  }
+
+  if (!SymtabLCI)
+    return Error("no symbol table found in object");
+  if (!SegmentLCI)
+    return Error("no symbol table found in object");
+
+  // Read and register the symbol table data.
+  InMemoryStruct<macho::SymtabLoadCommand> SymtabLC;
+  Obj->ReadSymtabLoadCommand(*SymtabLCI, SymtabLC);
+  if (!SymtabLC)
+    return Error("unable to load symbol table load command");
+  Obj->RegisterStringTable(*SymtabLC);
+
+  // Read the dynamic link-edit information, if present (not present in static
+  // objects).
+  if (DysymtabLCI) {
+    InMemoryStruct<macho::DysymtabLoadCommand> DysymtabLC;
+    Obj->ReadDysymtabLoadCommand(*DysymtabLCI, DysymtabLC);
+    if (!DysymtabLC)
+      return Error("unable to load dynamic link-exit load command");
+
+    // FIXME: We don't support anything interesting yet.
+//    if (DysymtabLC->LocalSymbolsIndex != 0)
+//      return Error("NOT YET IMPLEMENTED: local symbol entries");
+//    if (DysymtabLC->ExternalSymbolsIndex != 0)
+//      return Error("NOT YET IMPLEMENTED: non-external symbol entries");
+//    if (DysymtabLC->UndefinedSymbolsIndex != SymtabLC->NumSymbolTableEntries)
+//      return Error("NOT YET IMPLEMENTED: undefined symbol entries");
+  }
+
+  // Load the segment load command.
+  if (SegmentLCI->Command.Type == macho::LCT_Segment) {
+    if (loadSegment32(Obj.get(), SegmentLCI, SymtabLC))
+      return true;
+  } else {
+    if (loadSegment64(Obj.get(), SegmentLCI, SymtabLC))
+      return true;
+  }
+
+  return false;
+}
+
+// Assign an address to a symbol name and resolve all the relocations
+// associated with it.
+void RuntimeDyldMachO::reassignSymbolAddress(StringRef Name, uint8_t *Addr) {
+  // Assign the address in our symbol table.
+  SymbolTable[Name] = Addr;
+
+  RelocationList &Relocs = Relocations[Name];
+  for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
+    RelocationEntry &RE = Relocs[i];
+    uint8_t *Target = SymbolTable[RE.Target] + RE.Offset;
+    bool isPCRel = (RE.Data >> 24) & 1;
+    unsigned Type = (RE.Data >> 28) & 0xf;
+    unsigned Size = 1 << ((RE.Data >> 25) & 3);
+
+    DEBUG(dbgs() << "Resolving relocation at '" << RE.Target
+          << "' + " << RE.Offset << " (" << format("%p", Target) << ")"
+          << " from '" << Name << " (" << format("%p", Addr) << ")"
+          << "(" << (isPCRel ? "pcrel" : "absolute")
+          << ", type: " << Type << ", Size: " << Size << ").\n");
+
+    resolveRelocation(Target, Addr, isPCRel, Type, Size);
+    RE.isResolved = true;
+  }
+}
+
+bool RuntimeDyldMachO::isKnownFormat(const MemoryBuffer *InputBuffer) {
+  StringRef Magic = InputBuffer->getBuffer().slice(0, 4);
+  if (Magic == "\xFE\xED\xFA\xCE") return true;
+  if (Magic == "\xCE\xFA\xED\xFE") return true;
+  if (Magic == "\xFE\xED\xFA\xCF") return true;
+  if (Magic == "\xCF\xFA\xED\xFE") return true;
+  return false;
+}
+
+} // end namespace llvm