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diff --git a/lib/ExecutionEngine/JIT/JIT.cpp b/lib/ExecutionEngine/JIT/JIT.cpp
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+++ b/lib/ExecutionEngine/JIT/JIT.cpp
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+//===-- JIT.cpp - LLVM Just in Time Compiler ------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This tool implements a just-in-time compiler for LLVM, allowing direct
+// execution of LLVM bytecode in an efficient manner.
+//
+//===----------------------------------------------------------------------===//
+
+#include "JIT.h"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Function.h"
+#include "llvm/GlobalVariable.h"
+#include "llvm/Instructions.h"
+#include "llvm/ModuleProvider.h"
+#include "llvm/CodeGen/MachineCodeEmitter.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/ExecutionEngine/GenericValue.h"
+#include "llvm/System/DynamicLibrary.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetJITInfo.h"
+#include <iostream>
+
+using namespace llvm;
+
+JIT::JIT(ModuleProvider *MP, TargetMachine &tm, TargetJITInfo &tji)
+  : ExecutionEngine(MP), TM(tm), TJI(tji), state(MP) {
+  setTargetData(TM.getTargetData());
+
+  // Initialize MCE
+  MCE = createEmitter(*this);
+
+  // Add target data
+  MutexGuard locked(lock);
+  FunctionPassManager& PM = state.getPM(locked);
+  PM.add(new TargetData(TM.getTargetData()));
+
+  // Compile LLVM Code down to machine code in the intermediate representation
+  TJI.addPassesToJITCompile(PM);
+
+  // Turn the machine code intermediate representation into bytes in memory that
+  // may be executed.
+  if (TM.addPassesToEmitMachineCode(PM, *MCE)) {
+    std::cerr << "Target '" << TM.getName()
+              << "' doesn't support machine code emission!\n";
+    abort();
+  }
+}
+
+JIT::~JIT() {
+  delete MCE;
+  delete &TM;
+}
+
+/// run - Start execution with the specified function and arguments.
+///
+GenericValue JIT::runFunction(Function *F,
+                              const std::vector<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");
+  const FunctionType *FTy = F->getFunctionType();
+  const Type *RetTy = FTy->getReturnType();
+
+  assert((FTy->getNumParams() <= ArgValues.size() || FTy->isVarArg()) &&
+         "Too many 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 == Type::IntTy || RetTy == Type::UIntTy || RetTy == Type::VoidTy) {
+    switch (ArgValues.size()) {
+    case 3:
+      if ((FTy->getParamType(0) == Type::IntTy ||
+           FTy->getParamType(0) == Type::UIntTy) &&
+          isa<PointerType>(FTy->getParamType(1)) &&
+          isa<PointerType>(FTy->getParamType(2))) {
+        int (*PF)(int, char **, const char **) =
+          (int(*)(int, char **, const char **))FPtr;
+
+        // Call the function.
+        GenericValue rv;
+        rv.IntVal = PF(ArgValues[0].IntVal, (char **)GVTOP(ArgValues[1]),
+                       (const char **)GVTOP(ArgValues[2]));
+        return rv;
+      }
+      break;
+    case 2:
+      if ((FTy->getParamType(0) == Type::IntTy ||
+           FTy->getParamType(0) == Type::UIntTy) &&
+          isa<PointerType>(FTy->getParamType(1))) {
+        int (*PF)(int, char **) = (int(*)(int, char **))FPtr;
+
+        // Call the function.
+        GenericValue rv;
+        rv.IntVal = PF(ArgValues[0].IntVal, (char **)GVTOP(ArgValues[1]));
+        return rv;
+      }
+      break;
+    case 1:
+      if (FTy->getNumParams() == 1 &&
+          (FTy->getParamType(0) == Type::IntTy ||
+           FTy->getParamType(0) == Type::UIntTy)) {
+        GenericValue rv;
+        int (*PF)(int) = (int(*)(int))FPtr;
+        rv.IntVal = PF(ArgValues[0].IntVal);
+        return rv;
+      }
+      break;
+    }
+  }
+
+  // Handle cases where no arguments are passed first.
+  if (ArgValues.empty()) {
+    GenericValue rv;
+    switch (RetTy->getTypeID()) {
+    default: assert(0 && "Unknown return type for function call!");
+    case Type::BoolTyID:
+      rv.BoolVal = ((bool(*)())FPtr)();
+      return rv;
+    case Type::SByteTyID:
+    case Type::UByteTyID:
+      rv.SByteVal = ((char(*)())FPtr)();
+      return rv;
+    case Type::ShortTyID:
+    case Type::UShortTyID:
+      rv.ShortVal = ((short(*)())FPtr)();
+      return rv;
+    case Type::VoidTyID:
+    case Type::IntTyID:
+    case Type::UIntTyID:
+      rv.IntVal = ((int(*)())FPtr)();
+      return rv;
+    case Type::LongTyID:
+    case Type::ULongTyID:
+      rv.LongVal = ((int64_t(*)())FPtr)();
+      return rv;
+    case Type::FloatTyID:
+      rv.FloatVal = ((float(*)())FPtr)();
+      return rv;
+    case Type::DoubleTyID:
+      rv.DoubleVal = ((double(*)())FPtr)();
+      return rv;
+    case Type::PointerTyID:
+      return PTOGV(((void*(*)())FPtr)());
+    }
+  }
+
+  // Okay, this is not one of our quick and easy cases.  Because we don't have a
+  // full FFI, we have to codegen a nullary stub function that just calls the
+  // function we are interested in, passing in constants for all of the
+  // arguments.  Make this function and return.
+
+  // First, create the function.
+  FunctionType *STy=FunctionType::get(RetTy, std::vector<const Type*>(), false);
+  Function *Stub = new Function(STy, Function::InternalLinkage, "",
+                                F->getParent());
+
+  // Insert a basic block.
+  BasicBlock *StubBB = new BasicBlock("", Stub);
+
+  // Convert all of the GenericValue arguments over to constants.  Note that we
+  // currently don't support varargs.
+  std::vector<Value*> Args;
+  for (unsigned i = 0, e = ArgValues.size(); i != e; ++i) {
+    Constant *C = 0;
+    const Type *ArgTy = FTy->getParamType(i);
+    const GenericValue &AV = ArgValues[i];
+    switch (ArgTy->getTypeID()) {
+    default: assert(0 && "Unknown argument type for function call!");
+    case Type::BoolTyID:   C = ConstantBool::get(AV.BoolVal); break;
+    case Type::SByteTyID:  C = ConstantSInt::get(ArgTy, AV.SByteVal);  break;
+    case Type::UByteTyID:  C = ConstantUInt::get(ArgTy, AV.UByteVal);  break;
+    case Type::ShortTyID:  C = ConstantSInt::get(ArgTy, AV.ShortVal);  break;
+    case Type::UShortTyID: C = ConstantUInt::get(ArgTy, AV.UShortVal); break;
+    case Type::IntTyID:    C = ConstantSInt::get(ArgTy, AV.IntVal);    break;
+    case Type::UIntTyID:   C = ConstantUInt::get(ArgTy, AV.UIntVal);   break;
+    case Type::LongTyID:   C = ConstantSInt::get(ArgTy, AV.LongVal);   break;
+    case Type::ULongTyID:  C = ConstantUInt::get(ArgTy, AV.ULongVal);  break;
+    case Type::FloatTyID:  C = ConstantFP  ::get(ArgTy, AV.FloatVal);  break;
+    case Type::DoubleTyID: C = ConstantFP  ::get(ArgTy, AV.DoubleVal); break;
+    case Type::PointerTyID:
+      void *ArgPtr = GVTOP(AV);
+      if (sizeof(void*) == 4) {
+        C = ConstantSInt::get(Type::IntTy, (int)(intptr_t)ArgPtr);
+      } else {
+        C = ConstantSInt::get(Type::LongTy, (intptr_t)ArgPtr);
+      }
+      C = ConstantExpr::getCast(C, ArgTy);  // Cast the integer to pointer
+      break;
+    }
+    Args.push_back(C);
+  }
+
+  CallInst *TheCall = new CallInst(F, Args, "", StubBB);
+  TheCall->setTailCall();
+  if (TheCall->getType() != Type::VoidTy)
+    new ReturnInst(TheCall, StubBB);             // Return result of the call.
+  else
+    new ReturnInst(StubBB);                      // Just return void.
+
+  // Finally, return the value returned by our nullary stub function.
+  return runFunction(Stub, std::vector<GenericValue>());
+}
+
+/// runJITOnFunction - Run the FunctionPassManager full of
+/// just-in-time compilation passes on F, hopefully filling in
+/// GlobalAddress[F] with the address of F's machine code.
+///
+void JIT::runJITOnFunction(Function *F) {
+  static bool isAlreadyCodeGenerating = false;
+  assert(!isAlreadyCodeGenerating && "Error: Recursive compilation detected!");
+
+  MutexGuard locked(lock);
+
+  // JIT the function
+  isAlreadyCodeGenerating = true;
+  state.getPM(locked).run(*F);
+  isAlreadyCodeGenerating = false;
+
+  // If the function referred to a global variable that had not yet been
+  // emitted, it allocates memory for the global, but doesn't emit it yet.  Emit
+  // all of these globals now.
+  while (!state.getPendingGlobals(locked).empty()) {
+    const GlobalVariable *GV = state.getPendingGlobals(locked).back();
+    state.getPendingGlobals(locked).pop_back();
+    EmitGlobalVariable(GV);
+  }
+}
+
+/// getPointerToFunction - This method is used to get the address of the
+/// specified function, compiling it if neccesary.
+///
+void *JIT::getPointerToFunction(Function *F) {
+  MutexGuard locked(lock);
+
+  if (void *Addr = getPointerToGlobalIfAvailable(F))
+    return Addr;   // Check if function already code gen'd
+
+  // Make sure we read in the function if it exists in this Module
+  if (F->hasNotBeenReadFromBytecode())
+    try {
+      MP->materializeFunction(F);
+    } catch ( std::string& errmsg ) {
+      std::cerr << "Error reading function '" << F->getName()
+                << "' from bytecode file: " << errmsg << "\n";
+      abort();
+    } catch (...) {
+      std::cerr << "Error reading function '" << F->getName()
+                << "from bytecode file!\n";
+      abort();
+    }
+
+  if (F->isExternal()) {
+    void *Addr = getPointerToNamedFunction(F->getName());
+    addGlobalMapping(F, Addr);
+    return Addr;
+  }
+
+  runJITOnFunction(F);
+
+  void *Addr = getPointerToGlobalIfAvailable(F);
+  assert(Addr && "Code generation didn't add function to GlobalAddress table!");
+  return Addr;
+}
+
+/// getOrEmitGlobalVariable - Return the address of the specified global
+/// variable, possibly emitting it to memory if needed.  This is used by the
+/// Emitter.
+void *JIT::getOrEmitGlobalVariable(const GlobalVariable *GV) {
+  MutexGuard locked(lock);
+
+  void *Ptr = getPointerToGlobalIfAvailable(GV);
+  if (Ptr) return Ptr;
+
+  // If the global is external, just remember the address.
+  if (GV->isExternal()) {
+    Ptr = sys::DynamicLibrary::SearchForAddressOfSymbol(GV->getName().c_str());
+    if (Ptr == 0) {
+      std::cerr << "Could not resolve external global address: "
+                << GV->getName() << "\n";
+      abort();
+    }
+  } else {
+    // If the global hasn't been emitted to memory yet, allocate space.  We will
+    // actually initialize the global after current function has finished
+    // compilation.
+    uint64_t S = getTargetData().getTypeSize(GV->getType()->getElementType());
+    unsigned char A =  getTargetData().getTypeAlignment(GV->getType()->getElementType());
+    Ptr = MCE->allocateGlobal(S, A);
+    state.getPendingGlobals(locked).push_back(GV);
+  }
+  addGlobalMapping(GV, Ptr);
+  return Ptr;
+}
+
+
+/// recompileAndRelinkFunction - This method is used to force a function
+/// which has already been compiled, to be compiled again, possibly
+/// after it has been modified. Then the entry to the old copy is overwritten
+/// with a branch to the new copy. If there was no old copy, this acts
+/// just like JIT::getPointerToFunction().
+///
+void *JIT::recompileAndRelinkFunction(Function *F) {
+  void *OldAddr = getPointerToGlobalIfAvailable(F);
+
+  // If it's not already compiled there is no reason to patch it up.
+  if (OldAddr == 0) { return getPointerToFunction(F); }
+
+  // Delete the old function mapping.
+  addGlobalMapping(F, 0);
+
+  // Recodegen the function
+  runJITOnFunction(F);
+
+  // Update state, forward the old function to the new function.
+  void *Addr = getPointerToGlobalIfAvailable(F);
+  assert(Addr && "Code generation didn't add function to GlobalAddress table!");
+  TJI.replaceMachineCodeForFunction(OldAddr, Addr);
+  return Addr;
+}
+
+/// freeMachineCodeForFunction - release machine code memory for given Function
+///
+void JIT::freeMachineCodeForFunction(Function *F) {
+  // currently a no-op
+}