diff --git a/include/llvm/ExecutionEngine/ExecutionEngine.h b/include/llvm/ExecutionEngine/ExecutionEngine.h
index 0e51271c6f2..ce80d1c6768 100644
--- a/include/llvm/ExecutionEngine/ExecutionEngine.h
+++ b/include/llvm/ExecutionEngine/ExecutionEngine.h
@@ -126,8 +126,8 @@ protected:
   virtual char *getMemoryForGV(const GlobalVariable *GV);
 
   // To avoid having libexecutionengine depend on the JIT and interpreter
-  // libraries, the JIT and Interpreter set these functions to ctor pointers at
-  // startup time if they are linked in.
+  // libraries, the execution engine implementations set these functions to ctor
+  // pointers at startup time if they are linked in.
   static ExecutionEngine *(*JITCtor)(
     Module *M,
     std::string *ErrorStr,
@@ -138,6 +138,16 @@ protected:
     StringRef MArch,
     StringRef MCPU,
     const SmallVectorImpl<std::string>& MAttrs);
+  static ExecutionEngine *(*MCJITCtor)(
+    Module *M,
+    std::string *ErrorStr,
+    JITMemoryManager *JMM,
+    CodeGenOpt::Level OptLevel,
+    bool GVsWithCode,
+    CodeModel::Model CMM,
+    StringRef MArch,
+    StringRef MCPU,
+    const SmallVectorImpl<std::string>& MAttrs);
   static ExecutionEngine *(*InterpCtor)(Module *M,
                                         std::string *ErrorStr);
 
@@ -447,6 +457,7 @@ private:
   std::string MArch;
   std::string MCPU;
   SmallVector<std::string, 4> MAttrs;
+  bool UseMCJIT;
 
   /// InitEngine - Does the common initialization of default options.
   void InitEngine() {
@@ -456,6 +467,7 @@ private:
     JMM = NULL;
     AllocateGVsWithCode = false;
     CMModel = CodeModel::Default;
+    UseMCJIT = false;
   }
 
 public:
@@ -526,6 +538,12 @@ public:
     return *this;
   }
 
+  /// setUseMCJIT - Set whether the MC-JIT implementation should be used
+  /// (experimental).
+  void setUseMCJIT(bool Value) {
+    UseMCJIT = Value;
+  }
+
   /// setMAttrs - Set cpu-specific attributes.
   template<typename StringSequence>
   EngineBuilder &setMAttrs(const StringSequence &mattrs) {
diff --git a/lib/ExecutionEngine/ExecutionEngine.cpp b/lib/ExecutionEngine/ExecutionEngine.cpp
index fc5cb926e3b..91d68fb1e25 100644
--- a/lib/ExecutionEngine/ExecutionEngine.cpp
+++ b/lib/ExecutionEngine/ExecutionEngine.cpp
@@ -46,6 +46,16 @@ ExecutionEngine *(*ExecutionEngine::JITCtor)(
   StringRef MArch,
   StringRef MCPU,
   const SmallVectorImpl<std::string>& MAttrs) = 0;
+ExecutionEngine *(*ExecutionEngine::MCJITCtor)(
+  Module *M,
+  std::string *ErrorStr,
+  JITMemoryManager *JMM,
+  CodeGenOpt::Level OptLevel,
+  bool GVsWithCode,
+  CodeModel::Model CMM,
+  StringRef MArch,
+  StringRef MCPU,
+  const SmallVectorImpl<std::string>& MAttrs) = 0;
 ExecutionEngine *(*ExecutionEngine::InterpCtor)(Module *M,
                                                 std::string *ErrorStr) = 0;
 
@@ -430,7 +440,13 @@ ExecutionEngine *EngineBuilder::create() {
   // Unless the interpreter was explicitly selected or the JIT is not linked,
   // try making a JIT.
   if (WhichEngine & EngineKind::JIT) {
-    if (ExecutionEngine::JITCtor) {
+    if (UseMCJIT && ExecutionEngine::MCJITCtor) {
+      ExecutionEngine *EE =
+        ExecutionEngine::MCJITCtor(M, ErrorStr, JMM, OptLevel,
+                                   AllocateGVsWithCode, CMModel,
+                                   MArch, MCPU, MAttrs);
+      if (EE) return EE;
+    } else if (ExecutionEngine::JITCtor) {
       ExecutionEngine *EE =
         ExecutionEngine::JITCtor(M, ErrorStr, JMM, OptLevel,
                                  AllocateGVsWithCode, CMModel,
diff --git a/tools/lli/lli.cpp b/tools/lli/lli.cpp
index fa2de760627..507e38d9209 100644
--- a/tools/lli/lli.cpp
+++ b/tools/lli/lli.cpp
@@ -55,6 +55,10 @@ namespace {
                                  cl::desc("Force interpretation: disable JIT"),
                                  cl::init(false));
 
+  cl::opt<bool> UseMCJIT(
+    "use-mcjit", cl::desc("Enable use of the MC-based JIT (if available)"),
+    cl::init(false));
+
   // Determine optimization level.
   cl::opt<char>
   OptLevel("O",
@@ -167,6 +171,10 @@ int main(int argc, char **argv, char * const *envp) {
   if (!TargetTriple.empty())
     Mod->setTargetTriple(Triple::normalize(TargetTriple));
 
+  // Enable MCJIT, if desired.
+  if (UseMCJIT)
+    builder.setUseMCJIT(true);
+
   CodeGenOpt::Level OLvl = CodeGenOpt::Default;
   switch (OptLevel) {
   default: