diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -8719,7 +8719,7 @@
         // FIXME: We definitely want to re-use the existing MemoryBuffer, rather
         // than mmap the files several times.
         auto Entry =
-            ToFileManager.getFile(Cache->OrigEntry->getName());
+            ToFileManager.getOptionalFileRef(Cache->OrigEntry->getName());
         // FIXME: The filename may be a virtual name that does probably not
         // point to a valid file and we get no Entry here. In this case try with
         // the memory buffer below.