Index: lib/CodeGen/BackendUtil.cpp
===================================================================
--- lib/CodeGen/BackendUtil.cpp
+++ lib/CodeGen/BackendUtil.cpp
@@ -165,6 +165,11 @@
   PM.add(createSampleProfileLoaderPass(CGOpts.SampleProfileFile));
 }
 
+static void addAddDiscriminatorsPass(const PassManagerBuilder &Builder,
+                                     PassManagerBase &PM) {
+  PM.add(createAddDiscriminatorsPass());
+}
+
 static void addBoundsCheckingPass(const PassManagerBuilder &Builder,
                                     PassManagerBase &PM) {
   PM.add(createBoundsCheckingPass());
@@ -245,6 +250,9 @@
   PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
   PMBuilder.RerollLoops = CodeGenOpts.RerollLoops;
 
+  PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
+                         addAddDiscriminatorsPass);
+
   if (!CodeGenOpts.SampleProfileFile.empty())
     PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
                            addSampleProfileLoaderPass);