diff --git a/clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h b/clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h
index f7b4510d7f7beb..d12814e7c9253e 100644
--- a/clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h
+++ b/clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h
@@ -353,6 +353,12 @@ class DependencyScanningWorkerFilesystem
 
   std::error_code setCurrentWorkingDirectory(const Twine &Path) override;
 
+  /// Make it so that no paths bypass this VFS.
+  void resetBypassedPathPrefix() { BypassedPathPrefix.reset(); }
+  /// Set the prefix for paths that should bypass this VFS and go straight to
+  /// the underlying VFS.
+  void setBypassedPathPrefix(StringRef Prefix) { BypassedPathPrefix = Prefix; }
+
   /// Returns entry for the given filename.
   ///
   /// Attempts to use the local and shared caches first, then falls back to
@@ -450,12 +456,19 @@ class DependencyScanningWorkerFilesystem
     getUnderlyingFS().print(OS, Type, IndentLevel + 1);
   }
 
+  /// Whether this path should bypass this VFS and go straight to the underlying
+  /// VFS.
+  bool shouldBypass(StringRef Path) const;
+
   /// The global cache shared between worker threads.
   DependencyScanningFilesystemSharedCache &SharedCache;
   /// The local cache is used by the worker thread to cache file system queries
   /// locally instead of querying the global cache every time.
   DependencyScanningFilesystemLocalCache LocalCache;
 
+  /// Prefix of paths that should go straight to the underlying VFS.
+  std::optional<std::string> BypassedPathPrefix;
+
   /// The working directory to use for making relative paths absolute before
   /// using them for cache lookups.
   llvm::ErrorOr<std::string> WorkingDirForCacheLookup;
diff --git a/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp b/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
index 0cab17a3424406..4d738e4bea41a6 100644
--- a/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
+++ b/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
@@ -201,11 +201,8 @@ const CachedRealPath &DependencyScanningFilesystemSharedCache::CacheShard::
   return *StoredRealPath;
 }
 
-static bool shouldCacheStatFailures(StringRef Filename) {
-  StringRef Ext = llvm::sys::path::extension(Filename);
-  if (Ext.empty())
-    return false; // This may be the module cache directory.
-  return true;
+bool DependencyScanningWorkerFilesystem::shouldBypass(StringRef Path) const {
+  return BypassedPathPrefix && Path.starts_with(*BypassedPathPrefix);
 }
 
 DependencyScanningWorkerFilesystem::DependencyScanningWorkerFilesystem(
@@ -244,8 +241,6 @@ DependencyScanningWorkerFilesystem::computeAndStoreResult(
   llvm::ErrorOr<llvm::vfs::Status> Stat =
       getUnderlyingFS().status(OriginalFilename);
   if (!Stat) {
-    if (!shouldCacheStatFailures(OriginalFilename))
-      return Stat.getError();
     const auto &Entry =
         getOrEmplaceSharedEntryForFilename(FilenameForLookup, Stat.getError());
     return insertLocalEntryForFilename(FilenameForLookup, Entry);
@@ -291,7 +286,7 @@ DependencyScanningWorkerFilesystem::status(const Twine &Path) {
   SmallString<256> OwnedFilename;
   StringRef Filename = Path.toStringRef(OwnedFilename);
 
-  if (Filename.ends_with(".pcm"))
+  if (shouldBypass(Filename))
     return getUnderlyingFS().status(Path);
 
   llvm::ErrorOr<EntryRef> Result = getOrCreateFileSystemEntry(Filename);
@@ -362,7 +357,7 @@ DependencyScanningWorkerFilesystem::openFileForRead(const Twine &Path) {
   SmallString<256> OwnedFilename;
   StringRef Filename = Path.toStringRef(OwnedFilename);
 
-  if (Filename.ends_with(".pcm"))
+  if (shouldBypass(Filename))
     return getUnderlyingFS().openFileForRead(Path);
 
   llvm::ErrorOr<EntryRef> Result = getOrCreateFileSystemEntry(Filename);
@@ -377,6 +372,9 @@ DependencyScanningWorkerFilesystem::getRealPath(const Twine &Path,
   SmallString<256> OwnedFilename;
   StringRef OriginalFilename = Path.toStringRef(OwnedFilename);
 
+  if (shouldBypass(OriginalFilename))
+    return getUnderlyingFS().getRealPath(Path, Output);
+
   SmallString<256> PathBuf;
   auto FilenameForLookup = tryGetFilenameForLookup(OriginalFilename, PathBuf);
   if (!FilenameForLookup)
diff --git a/clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp b/clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp
index 91842627b001c2..1a21a4f5e30ff8 100644
--- a/clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp
+++ b/clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp
@@ -345,6 +345,26 @@ class DependencyScanningAction : public tooling::ToolAction {
         ScanInstance.getInvocation(), ScanInstance.getDiagnostics(),
         DriverFileMgr->getVirtualFileSystemPtr());
 
+    // Use the dependency scanning optimized file system if requested to do so.
+    if (DepFS) {
+      StringRef ModulesCachePath =
+          ScanInstance.getHeaderSearchOpts().ModuleCachePath;
+
+      DepFS->resetBypassedPathPrefix();
+      if (!ModulesCachePath.empty())
+        DepFS->setBypassedPathPrefix(ModulesCachePath);
+
+      ScanInstance.getPreprocessorOpts().DependencyDirectivesForFile =
+          [LocalDepFS = DepFS](FileEntryRef File)
+          -> std::optional<ArrayRef<dependency_directives_scan::Directive>> {
+        if (llvm::ErrorOr<EntryRef> Entry =
+                LocalDepFS->getOrCreateFileSystemEntry(File.getName()))
+          if (LocalDepFS->ensureDirectiveTokensArePopulated(*Entry))
+            return Entry->getDirectiveTokens();
+        return std::nullopt;
+      };
+    }
+
     // Create a new FileManager to match the invocation's FileSystemOptions.
     auto *FileMgr = ScanInstance.createFileManager(FS);
     ScanInstance.createSourceManager(*FileMgr);
@@ -361,18 +381,6 @@ class DependencyScanningAction : public tooling::ToolAction {
               PrebuiltModuleVFSMap, ScanInstance.getDiagnostics()))
         return false;
 
-    // Use the dependency scanning optimized file system if requested to do so.
-    if (DepFS)
-      ScanInstance.getPreprocessorOpts().DependencyDirectivesForFile =
-          [LocalDepFS = DepFS](FileEntryRef File)
-          -> std::optional<ArrayRef<dependency_directives_scan::Directive>> {
-        if (llvm::ErrorOr<EntryRef> Entry =
-                LocalDepFS->getOrCreateFileSystemEntry(File.getName()))
-          if (LocalDepFS->ensureDirectiveTokensArePopulated(*Entry))
-            return Entry->getDirectiveTokens();
-        return std::nullopt;
-      };
-
     // Create the dependency collector that will collect the produced
     // dependencies.
     //
diff --git a/clang/unittests/Tooling/DependencyScanning/DependencyScanningFilesystemTest.cpp b/clang/unittests/Tooling/DependencyScanning/DependencyScanningFilesystemTest.cpp
index 87bb67cfd9327c..29c0b36492a90b 100644
--- a/clang/unittests/Tooling/DependencyScanning/DependencyScanningFilesystemTest.cpp
+++ b/clang/unittests/Tooling/DependencyScanning/DependencyScanningFilesystemTest.cpp
@@ -174,3 +174,35 @@ TEST(DependencyScanningFilesystem, CacheStatOnExists) {
   EXPECT_EQ(InstrumentingFS->NumStatusCalls, 2u);
   EXPECT_EQ(InstrumentingFS->NumExistsCalls, 0u);
 }
+
+TEST(DependencyScanningFilesystem, CacheStatFailures) {
+  auto InMemoryFS = llvm::makeIntrusiveRefCnt<llvm::vfs::InMemoryFileSystem>();
+  InMemoryFS->setCurrentWorkingDirectory("/");
+  InMemoryFS->addFile("/dir/vector", 0, llvm::MemoryBuffer::getMemBuffer(""));
+  InMemoryFS->addFile("/cache/a.pcm", 0, llvm::MemoryBuffer::getMemBuffer(""));
+
+  auto InstrumentingFS =
+      llvm::makeIntrusiveRefCnt<InstrumentingFilesystem>(InMemoryFS);
+
+  DependencyScanningFilesystemSharedCache SharedCache;
+  DependencyScanningWorkerFilesystem DepFS(SharedCache, InstrumentingFS);
+
+  DepFS.status("/dir");
+  DepFS.status("/dir");
+  EXPECT_EQ(InstrumentingFS->NumStatusCalls, 1u);
+
+  DepFS.status("/dir/vector");
+  DepFS.status("/dir/vector");
+  EXPECT_EQ(InstrumentingFS->NumStatusCalls, 2u);
+
+  DepFS.setBypassedPathPrefix("/cache");
+  DepFS.exists("/cache/a.pcm");
+  EXPECT_EQ(InstrumentingFS->NumStatusCalls, 3u);
+  DepFS.exists("/cache/a.pcm");
+  EXPECT_EQ(InstrumentingFS->NumStatusCalls, 4u);
+
+  DepFS.resetBypassedPathPrefix();
+  DepFS.exists("/cache/a.pcm");
+  DepFS.exists("/cache/a.pcm");
+  EXPECT_EQ(InstrumentingFS->NumStatusCalls, 5u);
+}