diff --git a/lib/ExecutionEngine/ExecutionEngine.cpp b/lib/ExecutionEngine/ExecutionEngine.cpp
index e74fc32..e64af91 100644
--- a/lib/ExecutionEngine/ExecutionEngine.cpp
+++ b/lib/ExecutionEngine/ExecutionEngine.cpp
@@ -383,7 +383,7 @@
 ExecutionEngine *ExecutionEngine::create(ModuleProvider *MP,
                                          bool ForceInterpreter,
                                          std::string *ErrorStr,
-                                         bool Fast) {
+                                         unsigned OptLevel) {
   ExecutionEngine *EE = 0;
 
   // Make sure we can resolve symbols in the program as well. The zero arg
@@ -393,11 +393,11 @@
 
   // Unless the interpreter was explicitly selected, try making a JIT.
   if (!ForceInterpreter && JITCtor)
-    EE = JITCtor(MP, ErrorStr, Fast);
+    EE = JITCtor(MP, ErrorStr, OptLevel);
 
   // If we can't make a JIT, make an interpreter instead.
   if (EE == 0 && InterpCtor)
-    EE = InterpCtor(MP, ErrorStr, Fast);
+    EE = InterpCtor(MP, ErrorStr, OptLevel);
 
   return EE;
 }
diff --git a/lib/ExecutionEngine/ExecutionEngineBindings.cpp b/lib/ExecutionEngine/ExecutionEngineBindings.cpp
index 39bf601..57467c2 100644
--- a/lib/ExecutionEngine/ExecutionEngineBindings.cpp
+++ b/lib/ExecutionEngine/ExecutionEngineBindings.cpp
@@ -114,11 +114,11 @@
 
 int LLVMCreateJITCompiler(LLVMExecutionEngineRef *OutJIT,
                           LLVMModuleProviderRef MP,
-                          int Fast,
+                          unsigned OptLevel,
                           char **OutError) {
   std::string Error;
   if (ExecutionEngine *JIT = ExecutionEngine::createJIT(unwrap(MP), &Error, 0,
-                                                        Fast != 0)) {
+                                                        OptLevel)) {
     *OutJIT = wrap(JIT);
     return 0;
   }
diff --git a/lib/ExecutionEngine/Interpreter/Interpreter.cpp b/lib/ExecutionEngine/Interpreter/Interpreter.cpp
index ac0ee3f..c05eeac 100644
--- a/lib/ExecutionEngine/Interpreter/Interpreter.cpp
+++ b/lib/ExecutionEngine/Interpreter/Interpreter.cpp
@@ -37,7 +37,7 @@
 /// create - Create a new interpreter object.  This can never fail.
 ///
 ExecutionEngine *Interpreter::create(ModuleProvider *MP, std::string* ErrStr,
-                                     bool Fast /*unused*/) {
+                                     unsigned OptLevel /*unused*/) {
   // Tell this ModuleProvide to materialize and release the module
   if (!MP->materializeModule(ErrStr))
     // We got an error, just return 0
diff --git a/lib/ExecutionEngine/Interpreter/Interpreter.h b/lib/ExecutionEngine/Interpreter/Interpreter.h
index f9555b7..2e10e6b 100644
--- a/lib/ExecutionEngine/Interpreter/Interpreter.h
+++ b/lib/ExecutionEngine/Interpreter/Interpreter.h
@@ -108,7 +108,7 @@
   /// create - Create an interpreter ExecutionEngine. This can never fail.
   ///
   static ExecutionEngine *create(ModuleProvider *M, std::string *ErrorStr = 0,
-                                 bool Fast /*unused*/ = 0);
+                                 unsigned OptLevel /*unused*/ = 3);
 
   /// run - Start execution with the specified function and arguments.
   ///
diff --git a/lib/ExecutionEngine/JIT/JIT.cpp b/lib/ExecutionEngine/JIT/JIT.cpp
index 986ec91..93203a2 100644
--- a/lib/ExecutionEngine/JIT/JIT.cpp
+++ b/lib/ExecutionEngine/JIT/JIT.cpp
@@ -196,8 +196,8 @@
 ExecutionEngine *ExecutionEngine::createJIT(ModuleProvider *MP,
                                             std::string *ErrorStr,
                                             JITMemoryManager *JMM,
-                                            bool Fast) {
-  ExecutionEngine *EE = JIT::createJIT(MP, ErrorStr, JMM, Fast);
+                                            unsigned OptLevel) {
+  ExecutionEngine *EE = JIT::createJIT(MP, ErrorStr, JMM, OptLevel);
   if (!EE) return 0;
   
   // Make sure we can resolve symbols in the program as well. The zero arg
@@ -207,7 +207,7 @@
 }
 
 JIT::JIT(ModuleProvider *MP, TargetMachine &tm, TargetJITInfo &tji,
-         JITMemoryManager *JMM, bool Fast)
+         JITMemoryManager *JMM, unsigned OptLevel)
   : ExecutionEngine(MP), TM(tm), TJI(tji) {
   setTargetData(TM.getTargetData());
 
@@ -223,7 +223,7 @@
 
   // Turn the machine code intermediate representation into bytes in memory that
   // may be executed.
-  if (TM.addPassesToEmitMachineCode(PM, *MCE, Fast)) {
+  if (TM.addPassesToEmitMachineCode(PM, *MCE, OptLevel)) {
     cerr << "Target does not support machine code emission!\n";
     abort();
   }
@@ -272,7 +272,7 @@
 
     // Turn the machine code intermediate representation into bytes in memory
     // that may be executed.
-    if (TM.addPassesToEmitMachineCode(PM, *MCE, false /*fast*/)) {
+    if (TM.addPassesToEmitMachineCode(PM, *MCE, 3 /* OptLevel */)) {
       cerr << "Target does not support machine code emission!\n";
       abort();
     }
@@ -305,7 +305,7 @@
     
     // Turn the machine code intermediate representation into bytes in memory
     // that may be executed.
-    if (TM.addPassesToEmitMachineCode(PM, *MCE, false /*fast*/)) {
+    if (TM.addPassesToEmitMachineCode(PM, *MCE, 3 /* OptLevel */)) {
       cerr << "Target does not support machine code emission!\n";
       abort();
     }
@@ -337,7 +337,7 @@
     
     // Turn the machine code intermediate representation into bytes in memory
     // that may be executed.
-    if (TM.addPassesToEmitMachineCode(PM, *MCE, false /*fast*/)) {
+    if (TM.addPassesToEmitMachineCode(PM, *MCE, 3 /* OptLevel */)) {
       cerr << "Target does not support machine code emission!\n";
       abort();
     }
diff --git a/lib/ExecutionEngine/JIT/JIT.h b/lib/ExecutionEngine/JIT/JIT.h
index e0c74f8..b3ae82c 100644
--- a/lib/ExecutionEngine/JIT/JIT.h
+++ b/lib/ExecutionEngine/JIT/JIT.h
@@ -55,7 +55,7 @@
   JITState *jitstate;
 
   JIT(ModuleProvider *MP, TargetMachine &tm, TargetJITInfo &tji, 
-      JITMemoryManager *JMM, bool Fast);
+      JITMemoryManager *JMM, unsigned OptLevel);
 public:
   ~JIT();
 
@@ -71,8 +71,8 @@
   /// for the current target.  Otherwise, return null.
   ///
   static ExecutionEngine *create(ModuleProvider *MP, std::string *Err,
-                                 bool Fast = false) {
-    return createJIT(MP, Err, 0, Fast);
+                                 unsigned OptLevel = 3) {
+    return createJIT(MP, Err, 0, OptLevel);
   }
 
   virtual void addModuleProvider(ModuleProvider *MP);
@@ -148,7 +148,7 @@
   MachineCodeEmitter *getCodeEmitter() const { return MCE; }
   
   static ExecutionEngine *createJIT(ModuleProvider *MP, std::string *Err,
-                                    JITMemoryManager *JMM, bool Fast);
+                                    JITMemoryManager *JMM, unsigned OptLevel);
   
 private:
   static MachineCodeEmitter *createEmitter(JIT &J, JITMemoryManager *JMM);
diff --git a/lib/ExecutionEngine/JIT/TargetSelect.cpp b/lib/ExecutionEngine/JIT/TargetSelect.cpp
index 98819c1..7edd083 100644
--- a/lib/ExecutionEngine/JIT/TargetSelect.cpp
+++ b/lib/ExecutionEngine/JIT/TargetSelect.cpp
@@ -42,7 +42,7 @@
 /// available for the current target.  Otherwise, return null.
 ///
 ExecutionEngine *JIT::createJIT(ModuleProvider *MP, std::string *ErrorStr,
-                                JITMemoryManager *JMM, bool Fast) {
+                                JITMemoryManager *JMM, unsigned OptLevel) {
   const TargetMachineRegistry::entry *TheArch = MArch;
   if (TheArch == 0) {
     std::string Error;
@@ -74,7 +74,7 @@
 
   // If the target supports JIT code generation, return a new JIT now.
   if (TargetJITInfo *TJ = Target->getJITInfo())
-    return new JIT(MP, *Target, *TJ, JMM, Fast);
+    return new JIT(MP, *Target, *TJ, JMM, OptLevel);
 
   if (ErrorStr)
     *ErrorStr = "target does not support JIT code generation";