diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
index c9c76e5..349dd7b 100644
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -84,7 +84,8 @@
                                   llvm::StringRef ImplicitIncludePTH) {
   PTHManager *P = PP.getPTHManager();
   assert(P && "No PTHManager.");
-  const char *OriginalFile = P->getOriginalSourceFile();
+  // Null check 'P' in the corner case where it couldn't be created.
+  const char *OriginalFile = P ? P->getOriginalSourceFile() : 0;
 
   if (!OriginalFile) {
     PP.getDiagnostics().Report(diag::err_fe_pth_file_has_no_source_header)