diff --git a/clang/lib/Lex/HeaderSearch.cpp b/clang/lib/Lex/HeaderSearch.cpp
--- a/clang/lib/Lex/HeaderSearch.cpp
+++ b/clang/lib/Lex/HeaderSearch.cpp
@@ -1284,9 +1284,9 @@
   HeaderFileInfo *HFI = &FileInfo[FE->getUID()];
   // FIXME: Use a generation count to check whether this is really up to date.
   if (ExternalSource && !HFI->Resolved) {
+    HFI->Resolved = true;
     auto ExternalHFI = ExternalSource->GetHeaderFileInfo(FE);
     if (ExternalHFI.IsValid) {
-      HFI->Resolved = true;
       if (ExternalHFI.External)
         mergeHeaderFileInfo(*HFI, ExternalHFI);
     }
@@ -1316,9 +1316,9 @@
     if (!WantExternal && (!HFI->IsValid || HFI->External))
       return nullptr;
     if (!HFI->Resolved) {
+      HFI->Resolved = true;
       auto ExternalHFI = ExternalSource->GetHeaderFileInfo(FE);
       if (ExternalHFI.IsValid) {
-        HFI->Resolved = true;
         if (ExternalHFI.External)
           mergeHeaderFileInfo(*HFI, ExternalHFI);
       }