Index: lib/CodeGen/CGDebugInfo.cpp
===================================================================
--- lib/CodeGen/CGDebugInfo.cpp
+++ lib/CodeGen/CGDebugInfo.cpp
@@ -411,6 +411,10 @@
     // If the location is not valid then use main input file.
     return getOrCreateMainFile();
 
+  if (!getSource(SM, SM.getFileID(Loc)))
+    // If the source file is not valid then use main input file
+    return getOrCreateMainFile();
+
   // Cache the results.
   const char *fname = PLoc.getFilename();
   auto It = DIFileCache.find(fname);