diff --git a/include/swift/IRGen/Options.h b/include/swift/IRGen/Options.h
index bf218a2a739..c1f7d3889a3 100644
--- a/include/swift/IRGen/Options.h
+++ b/include/swift/IRGen/Options.h
@@ -56,7 +56,11 @@ public:
   /// The optimization level, as in -O2.
   unsigned OptLevel : 2;
 
-  Options() : OutputKind(OutputKind::LLVMAssembly), Verify(true), OptLevel(0) {}
+  /// \brief Whether we're generating IR for the JIT.
+  unsigned UseJIT : 1;
+
+  Options() : OutputKind(OutputKind::LLVMAssembly), Verify(true), OptLevel(0),
+              UseJIT(false) {}
 };
 
 } // end namespace irgen
diff --git a/lib/IRGen/GenObjC.cpp b/lib/IRGen/GenObjC.cpp
index 686b5592f62..ac2259c467c 100644
--- a/lib/IRGen/GenObjC.cpp
+++ b/lib/IRGen/GenObjC.cpp
@@ -18,6 +18,7 @@
 #include "llvm/DerivedTypes.h"
 #include "llvm/Module.h"
 
+#include "swift/IRGen/Options.h"
 #include "swift/AST/Decl.h"
 #include "swift/AST/Types.h"
 
@@ -68,6 +69,17 @@ llvm::Constant *IRGenModule::getObjCMsgSendStretFn() {
   return ObjCMsgSendStretFn;
 }
 
+llvm::Constant *IRGenModule::getObjCSelRegisterNameFn() {
+  if (ObjCSelRegisterNameFn) return ObjCSelRegisterNameFn;
+
+  // SEL sel_registerName(const char *str);
+  llvm::Type *argTypes[1] = { Int8PtrTy };
+  auto fnType = llvm::FunctionType::get(Int8PtrTy, argTypes, false);
+  ObjCSelRegisterNameFn = createObjCRuntimeFunction(*this, "sel_registerName",
+                                                    fnType);
+  return ObjCSelRegisterNameFn;
+}
+
 #define DEFINE_OBJC_RUNTIME_FUNCTION(LABEL, NAME, RETTY)            \
 llvm::Constant *IRGenModule::getObjC##LABEL##Fn() {                 \
   if (ObjC##LABEL##Fn) return ObjC##LABEL##Fn;                      \
@@ -418,10 +430,24 @@ CallEmission irgen::prepareObjCMethodCall(IRGenFunction &IGF, FuncDecl *method,
   selfValues.addUnmanaged(value.getValue());
 
   // Add the selector value.
+  llvm::Value *selectorV;
   Selector selector(method);
-  auto selectorRef = IGF.IGM.getAddrOfObjCSelectorRef(selector.str());
-  auto selectorV =
-    IGF.Builder.CreateLoad(Address(selectorRef, IGF.IGM.getPointerAlignment()));
+  if (IGF.IGM.Opts.UseJIT) {
+    // When generating JIT'd code, we need to call sel_registerName() to force
+    // the runtime to unique the selector.
+    auto selectorRef = IGF.IGM.getAddrOfObjCSelectorRef(selector.str());
+    selectorV = IGF.Builder.CreateLoad(Address(selectorRef,
+                                               IGF.IGM.getPointerAlignment()));
+    selectorV = IGF.Builder.CreateCall(IGF.IGM.getObjCSelRegisterNameFn(),
+                                       selectorV);
+  } else {
+    // When generating statically-compiled code, just build a reference to
+    // the selector.
+    auto selectorRef = IGF.IGM.getAddrOfObjCSelectorRef(selector.str());
+    selectorV = IGF.Builder.CreateLoad(Address(selectorRef,
+                                               IGF.IGM.getPointerAlignment()));
+  }
+  
   selfValues.addUnmanaged(selectorV);
 
   // Add that to the emission.
diff --git a/lib/IRGen/IRGenModule.h b/lib/IRGen/IRGenModule.h
index 0c21fd9f9f2..ae37657db40 100644
--- a/lib/IRGen/IRGenModule.h
+++ b/lib/IRGen/IRGenModule.h
@@ -208,6 +208,8 @@ public:
   llvm::Constant *getObjCMsgSendFn();
   llvm::Constant *getObjCMsgSendStretFn();
 
+  llvm::Constant *getObjCSelRegisterNameFn();
+
   llvm::Constant *getGetFunctionMetadataFn();
   llvm::Constant *getGetGenericMetadataFn();
   llvm::Constant *getGetMetatypeMetadataFn();
@@ -232,6 +234,7 @@ private:
   llvm::Constant *ObjCReleaseFn = nullptr;
   llvm::Constant *ObjCMsgSendFn = nullptr;
   llvm::Constant *ObjCMsgSendStretFn = nullptr;
+  llvm::Constant *ObjCSelRegisterNameFn = nullptr;
 
 //--- Generic ---------------------------------------------------------------
 public:
diff --git a/tools/swift/Immediate.cpp b/tools/swift/Immediate.cpp
index bb3f8e0fc41..1ef32e8597a 100644
--- a/tools/swift/Immediate.cpp
+++ b/tools/swift/Immediate.cpp
@@ -143,7 +143,8 @@ void swift::RunImmediately(TranslationUnit *TU) {
   Options.Triple = llvm::sys::getDefaultTargetTriple();
   Options.OptLevel = 2;
   Options.OutputKind = irgen::OutputKind::Module;
-
+  Options.UseJIT = true;
+  
   // IRGen the main module.
   llvm::LLVMContext LLVMContext;
   llvm::Module Module(TU->Name.str(), LLVMContext);
@@ -299,7 +300,8 @@ void swift::REPL(ASTContext &Context) {
   Options.Triple = llvm::sys::getDefaultTargetTriple();
   Options.OptLevel = 0;
   Options.OutputKind = irgen::OutputKind::Module;
-
+  Options.UseJIT = true;
+  
   EditLineWrapper e;
 
   char* CurBuffer = const_cast<char*>(Buffer->getBufferStart());