Index: lib/Support/StringSaver.cpp
===================================================================
--- lib/Support/StringSaver.cpp
+++ lib/Support/StringSaver.cpp
@@ -12,6 +12,8 @@
 using namespace llvm;
 
 StringRef StringSaver::save(StringRef S) {
+  if (S.empty())
+    return StringRef();
   char *P = Alloc.Allocate<char>(S.size() + 1);
   memcpy(P, S.data(), S.size());
   P[S.size()] = '\0';