diff --git a/lib/Basic/FileManager.cpp b/lib/Basic/FileManager.cpp
index 75333f8..16906de 100644
--- a/lib/Basic/FileManager.cpp
+++ b/lib/Basic/FileManager.cpp
@@ -111,6 +111,8 @@
   }
 
   size_t size() const { return UniqueFiles.size(); }
+
+  friend class FileManager;
 };
 
 //===----------------------------------------------------------------------===//
@@ -152,6 +154,8 @@
   }
 
   size_t size() const { return UniqueFiles.size(); }
+
+  friend class FileManager;
 };
 
 #endif
@@ -559,6 +563,15 @@
   return ::stat(FilePath.c_str(), &StatBuf) != 0;
 }
 
+void FileManager::InvalidateCache(const FileEntry* Entry) {
+  if (!Entry)
+    return;
+
+  SeenFileEntries.erase(Entry->getName());
+  UniqueRealFiles.UniqueFiles.erase(*Entry);
+}
+
+
 void FileManager::GetUniqueIDMapping(
                    SmallVectorImpl<const FileEntry *> &UIDToFiles) const {
   UIDToFiles.clear();