diff --git a/clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp b/clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp
--- a/clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp
+++ b/clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp
@@ -177,6 +177,9 @@
     ScanInstance.getPreprocessorOpts().AllowPCHWithDifferentModulesCachePath =
         true;
 
+    ScanInstance.getFrontendOpts().GenerateGlobalModuleIndex = false;
+    ScanInstance.getFrontendOpts().UseGlobalModuleIndex = false;
+
     FileMgr->getFileSystemOpts().WorkingDir = std::string(WorkingDirectory);
     ScanInstance.setFileManager(FileMgr);
     ScanInstance.createSourceManager(*FileMgr);