Index: lib/Frontend/CompilerInstance.cpp
===================================================================
--- lib/Frontend/CompilerInstance.cpp
+++ lib/Frontend/CompilerInstance.cpp
@@ -1096,6 +1096,7 @@
         diagnoseBuildFailure();
         return false;
       }
+      ModuleLoadCapabilities |= ASTReader::ARR_OutOfDate;
       break;
 
     case llvm::LockFileManager::LFS_Shared:
@@ -1124,10 +1125,14 @@
             ModuleLoadCapabilities);
 
     if (ReadResult == ASTReader::OutOfDate &&
-        Locked == llvm::LockFileManager::LFS_Shared) {
+        (Locked == llvm::LockFileManager::LFS_Shared ||
+         Locked == llvm::LockFileManager::LFS_Owned)) {
       // The module may be out of date in the presence of file system races,
       // or if one of its imports depends on header search paths that are not
       // consistent with this ImportingInstance.  Try again...
+
+      // The module may be out of date right after we rebuild it if a module
+      // it imports is overwritten by another process. Try again...
       continue;
     } else if (ReadResult == ASTReader::Missing) {
       diagnoseBuildFailure();