Index: lib/Transforms/IPO/PassManagerBuilder.cpp
===================================================================
--- lib/Transforms/IPO/PassManagerBuilder.cpp
+++ lib/Transforms/IPO/PassManagerBuilder.cpp
@@ -556,6 +556,14 @@
   // Delete basic blocks, which optimization passes may have killed.
   PM.add(createCFGSimplificationPass());
 
+  // Remove avail extern fns and globals definitions. Note if they
+  // are unreferenced they will be removed by GlobalDCE below, so
+  // this only impacts referenced available externally globals.
+  // Eventually they will be suppressed during codegen, but eliminating
+  // here enables more opportunity for GlobalDCE as it may make
+  // globals referenced by available external functions dead.
+  PM.add(createEliminateAvailableExternallyPass());
+
   // Now that we have optimized the program, discard unreachable functions.
   PM.add(createGlobalDCEPass());