diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index eb75329..001a6ac 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -2402,6 +2402,12 @@
   if (getLangOpts().CPlusPlus)
     return MergeCXXFunctionDecl(New, Old, S);
 
+  // Merge the function types so the we get the composite types for the return
+  // and argument types.
+  QualType Merged = Context.mergeTypes(Old->getType(), New->getType());
+  if (!Merged.isNull())
+    New->setType(Merged);
+
   return false;
 }