Index: lib/CodeGen/CGDebugInfo.cpp
===================================================================
--- lib/CodeGen/CGDebugInfo.cpp
+++ lib/CodeGen/CGDebugInfo.cpp
@@ -421,13 +421,18 @@
       return cast<llvm::DIFile>(V);
   }
 
+  const FileID foundIdFromLoc = SM.getFileID(Loc);
   SmallString<32> Checksum;
-  Optional<llvm::DIFile::ChecksumKind> CSKind =
-      computeChecksum(SM.getFileID(Loc), Checksum);
+  Optional<llvm::DIFile::ChecksumKind> CSKind;
   Optional<llvm::DIFile::ChecksumInfo<StringRef>> CSInfo;
-  if (CSKind)
-    CSInfo.emplace(*CSKind, Checksum);
-  return createFile(FileName, CSInfo, getSource(SM, SM.getFileID(Loc)));
+  const FileEntry *fileEntry = SM.getFileEntryForID(foundIdFromLoc);
+  if (!fileEntry || fileEntry->getName().empty() ||
+      fileEntry->getName().equals(FileName)) {
+    CSKind = computeChecksum(foundIdFromLoc, Checksum);
+    if (CSKind)
+      CSInfo.emplace(*CSKind, Checksum);
+  }
+  return createFile(FileName, CSInfo, getSource(SM, foundIdFromLoc));
 }
 
 llvm::DIFile *
Index: test/Driver/cl-preprocess-md5.cpp
===================================================================
--- test/Driver/cl-preprocess-md5.cpp
+++ test/Driver/cl-preprocess-md5.cpp
@@ -0,0 +1,15 @@
+// RUN: %clang_cl /c %s /Z7 /Fo%t.obj
+// RUN: llvm-pdbutil dump -l %t.obj | grep -E " \(MD5: ([0-9A-F]+)\)" | sed -n -e 's/^.*MD5: //p' | sort | uniq | wc -l | FileCheck %s --check-prefix=GOOD-SIZE
+// GOOD-SIZE-NOT: 1
+
+// RUN: %clang_cl /c %s /Z7 /E >%t.cpp
+// RUN: %clang_cl /c %t.cpp /Z7 /Fo%t.obj
+// RUN: llvm-pdbutil dump -l %t.obj | not grep -E " \(MD5: ([0-9A-F]+)\)"
+// RUN: llvm-pdbutil dump -l %t.obj | grep " (no checksum)"
+// 
+
+#include <string>
+int main() {
+  std::string A{"a"};
+  return 0;
+}