diff --git a/clang/lib/Frontend/CodeGenAction.cpp b/clang/lib/Frontend/CodeGenAction.cpp
index 86005f2..03e3ea6 100644
--- a/clang/lib/Frontend/CodeGenAction.cpp
+++ b/clang/lib/Frontend/CodeGenAction.cpp
@@ -48,6 +48,7 @@
     Backend_EmitBC,        ///< Emit LLVM bitcode files
     Backend_EmitLL,        ///< Emit human-readable LLVM assembly
     Backend_EmitNothing,   ///< Don't emit anything (benchmarking mode)
+    Backend_EmitMCNull,    ///< Run CodeGen, but don't emit anything
     Backend_EmitObj        ///< Emit native object files
   };
 
@@ -340,6 +341,10 @@
   TargetMachine::CodeGenFileType CGFT = TargetMachine::CGFT_AssemblyFile;
   if (Action == Backend_EmitObj)
     CGFT = TargetMachine::CGFT_ObjectFile;
+  else if (Action == Backend_EmitMCNull)
+    CGFT = TargetMachine::CGFT_Null;
+  else
+    assert(Action == Backend_EmitAssembly && "Invalid action!");
   if (TM->addPassesToEmitFile(*PM, FormattedOutStream, CGFT, OptLevel,
                               /*DisableVerify=*/!CodeGenOpts.VerifyModule)) {
     Diags.Report(diag::err_fe_unable_to_interface_with_target);
@@ -557,6 +562,7 @@
     break;
   case Backend_EmitNothing:
     break;
+  case Backend_EmitMCNull:
   case Backend_EmitObj:
     OS.reset(CI.createDefaultOutputFile(true, InFile, "o"));
     break;
@@ -579,4 +585,6 @@
 
 EmitLLVMOnlyAction::EmitLLVMOnlyAction() : CodeGenAction(Backend_EmitNothing) {}
 
+EmitCodeGenOnlyAction::EmitCodeGenOnlyAction() : CodeGenAction(Backend_EmitMCNull) {}
+
 EmitObjAction::EmitObjAction() : CodeGenAction(Backend_EmitObj) {}