diff --git a/lib/ClangImporter/ClangImporter.cpp b/lib/ClangImporter/ClangImporter.cpp
index 43ea6cce93991..fb6df1a2ce585 100644
--- a/lib/ClangImporter/ClangImporter.cpp
+++ b/lib/ClangImporter/ClangImporter.cpp
@@ -1015,7 +1015,10 @@ bool ClangImporter::canReadPCH(StringRef PCHFilename) {
 
   // Note: Reusing the file manager is safe; this is a component that's already
   // reused when building PCM files for the module cache.
-  CI.createSourceManager(Impl.Instance->getFileManager());
+  CI.setVirtualFileSystem(
+      Impl.Instance->getFileManager().getVirtualFileSystemPtr());
+  CI.setFileManager(&Impl.Instance->getFileManager());
+  CI.createSourceManager();
   auto &clangSrcMgr = CI.getSourceManager();
   auto FID = clangSrcMgr.createFileID(
                         std::make_unique<ZeroFilledMemoryBuffer>(1, "<main>"));
@@ -1394,21 +1397,15 @@ std::unique_ptr<ClangImporter> ClangImporter::create(
   if (tracker)
     instance.addDependencyCollector(tracker->getClangCollector());
 
-  {
-    // Now set up the real client for Clang diagnostics---configured with proper
-    // options---as opposed to the temporary one we made above.
-    auto actualDiagClient = std::make_unique<ClangDiagnosticConsumer>(
-        importer->Impl, instance.getDiagnosticOpts(),
-        importerOpts.DumpClangDiagnostics);
-    instance.createDiagnostics(*VFS, actualDiagClient.release());
-  }
+  // Now set up the real client for Clang diagnostics---configured with proper
+  // options---as opposed to the temporary one we made above.
+  auto actualDiagClient = std::make_unique<ClangDiagnosticConsumer>(
+      importer->Impl, instance.getDiagnosticOpts(),
+      importerOpts.DumpClangDiagnostics);
 
-  // Set up the file manager.
-  {
-    VFS = clang::createVFSFromCompilerInvocation(
-        instance.getInvocation(), instance.getDiagnostics(), std::move(VFS));
-    instance.createFileManager(VFS);
-  }
+  instance.createVirtualFileSystem(std::move(VFS), actualDiagClient.get());
+  instance.createFileManager();
+  instance.createDiagnostics(actualDiagClient.release());
 
   // Don't stop emitting messages if we ever can't load a module.
   // FIXME: This is actually a general problem: any "fatal" error could mess up
@@ -1427,11 +1424,13 @@ std::unique_ptr<ClangImporter> ClangImporter::create(
   if (ctx.LangOpts.ClangTarget.has_value()) {
     // If '-clang-target' is set, create a mock invocation with the Swift triple
     // to configure CodeGen and Target options for Swift compilation.
-    auto swiftTargetClangArgs = importer->getClangCC1Arguments(ctx, VFS, true);
+    auto swiftTargetClangArgs = importer->getClangCC1Arguments(
+        ctx, instance.getVirtualFileSystemPtr(), true);
     if (!swiftTargetClangArgs)
       return nullptr;
     auto swiftTargetClangInvocation = createClangInvocation(
-        importer.get(), importerOpts, VFS, *swiftTargetClangArgs);
+        importer.get(), importerOpts, instance.getVirtualFileSystemPtr(),
+        *swiftTargetClangArgs);
     if (!swiftTargetClangInvocation)
       return nullptr;
 
@@ -1916,15 +1915,14 @@ std::string ClangImporter::getBridgingHeaderContents(
 
   invocation->getPreprocessorOpts().resetNonModularOptions();
 
-  clang::FileManager &fileManager = Impl.Instance->getFileManager();
-
   clang::CompilerInstance rewriteInstance(
       std::move(invocation), Impl.Instance->getPCHContainerOperations(),
       &Impl.Instance->getModuleCache());
-  rewriteInstance.createDiagnostics(fileManager.getVirtualFileSystem(),
-                                    new clang::IgnoringDiagConsumer);
-  rewriteInstance.setFileManager(&fileManager);
-  rewriteInstance.createSourceManager(fileManager);
+  rewriteInstance.setVirtualFileSystem(
+      Impl.Instance->getFileManager().getVirtualFileSystemPtr());
+  rewriteInstance.setFileManager(&Impl.Instance->getFileManager());
+  rewriteInstance.createDiagnostics(new clang::IgnoringDiagConsumer);
+  rewriteInstance.createSourceManager();
   rewriteInstance.setTarget(&Impl.Instance->getTarget());
 
   std::string result;
@@ -1972,7 +1970,8 @@ std::string ClangImporter::getBridgingHeaderContents(
     return "";
   }
 
-  if (auto fileInfo = fileManager.getOptionalFileRef(headerPath)) {
+  if (auto fileInfo =
+          rewriteInstance.getFileManager().getOptionalFileRef(headerPath)) {
     fileSize = fileInfo->getSize();
     fileModTime = fileInfo->getModificationTime();
   }
@@ -2021,16 +2020,15 @@ ClangImporter::cloneCompilerInstanceForPrecompiling() {
   // Share the CASOption and the underlying CAS.
   invocation->setCASOption(Impl.Invocation->getCASOptsPtr());
 
-  clang::FileManager &fileManager = Impl.Instance->getFileManager();
-
   auto clonedInstance = std::make_unique<clang::CompilerInstance>(
       std::move(invocation), Impl.Instance->getPCHContainerOperations(),
       &Impl.Instance->getModuleCache());
-  clonedInstance->createDiagnostics(fileManager.getVirtualFileSystem(),
-                                    &Impl.Instance->getDiagnosticClient(),
+  clonedInstance->setVirtualFileSystem(
+      Impl.Instance->getFileManager().getVirtualFileSystemPtr());
+  clonedInstance->setFileManager(&Impl.Instance->getFileManager());
+  clonedInstance->createDiagnostics(&Impl.Instance->getDiagnosticClient(),
                                     /*ShouldOwnClient=*/false);
-  clonedInstance->setFileManager(&fileManager);
-  clonedInstance->createSourceManager(fileManager);
+  clonedInstance->createSourceManager();
   clonedInstance->setTarget(&Impl.Instance->getTarget());
   clonedInstance->setOutputBackend(Impl.SwiftContext.OutputBackend);
 
diff --git a/lib/IRGen/IRGen.cpp b/lib/IRGen/IRGen.cpp
index 66b53079a3014..2268f9069e160 100644
--- a/lib/IRGen/IRGen.cpp
+++ b/lib/IRGen/IRGen.cpp
@@ -261,7 +261,6 @@ static std::optional<PGOOptions> buildIRUseOptions(const IRGenOptions &Opts,
       /*CSProfileGenFile=*/"",
       /*ProfileRemappingFile=*/"",
       /*MemoryProfile=*/"",
-      /*FS=*/FS,
       /*Action=*/PGOOptions::IRUse,
       /*CSPGOAction=*/IsCS ? PGOOptions::CSIRUse : PGOOptions::NoCSAction,
       /*ColdType=*/PGOOptions::ColdFuncOpt::Default,
@@ -277,7 +276,6 @@ static void populatePGOOptions(std::optional<PGOOptions> &Out,
       /*CSProfileGenFile=*/ "",
       /*ProfileRemappingFile=*/ "",
       /*MemoryProfile=*/ "",
-      /*FS=*/ llvm::vfs::getRealFileSystem(), // TODO: is this fine?
       /*Action=*/ PGOOptions::SampleUse,
       /*CSPGOAction=*/ PGOOptions::NoCSAction,
       /*ColdType=*/ PGOOptions::ColdFuncOpt::Default,
@@ -293,7 +291,6 @@ static void populatePGOOptions(std::optional<PGOOptions> &Out,
         /*CSProfileGenFile=*/Opts.InstrProfileOutput,
         /*ProfileRemappingFile=*/"",
         /*MemoryProfile=*/"",
-        /*FS=*/llvm::vfs::getRealFileSystem(),
         /*Action=*/hasUse ? PGOOptions::IRUse : PGOOptions::NoAction,
         /*CSPGOAction=*/PGOOptions::CSIRInstr,
         /*ColdType=*/PGOOptions::ColdFuncOpt::Default,
@@ -307,7 +304,6 @@ static void populatePGOOptions(std::optional<PGOOptions> &Out,
         /*CSProfileGenFile=*/"",
         /*ProfileRemappingFile=*/"",
         /*MemoryProfile=*/"",
-        /*FS=*/llvm::vfs::getRealFileSystem(),
         /*Action=*/PGOOptions::IRInstr,
         /*CSPGOAction=*/PGOOptions::NoCSAction,
         /*ColdType=*/PGOOptions::ColdFuncOpt::Default,
@@ -326,7 +322,6 @@ static void populatePGOOptions(std::optional<PGOOptions> &Out,
         /*CSProfileGenFile=*/ "",
         /*ProfileRemappingFile=*/ "",
         /*MemoryProfile=*/ "",
-        /*FS=*/ nullptr,
         /*Action=*/ PGOOptions::NoAction,
         /*CSPGOAction=*/ PGOOptions::NoCSAction,
         /*ColdType=*/ PGOOptions::ColdFuncOpt::Default,