Index: lib/Frontend/FrontendActions.cpp
===================================================================
--- lib/Frontend/FrontendActions.cpp
+++ lib/Frontend/FrontendActions.cpp
@@ -209,17 +209,18 @@
     std::error_code EC;
     SmallString<128> DirNative;
     llvm::sys::path::native(UmbrellaDir.Entry->getName(), DirNative);
-    for (llvm::sys::fs::recursive_directory_iterator Dir(DirNative, EC), 
-                                                     DirEnd;
-         Dir != DirEnd && !EC; Dir.increment(EC)) {
+
+    vfs::FileSystem &FS = *FileMgr.getVirtualFileSystem();
+    for (vfs::recursive_directory_iterator Dir(FS, DirNative, EC), End;
+         Dir != End && !EC; Dir.increment(EC)) {
       // Check whether this entry has an extension typically associated with 
       // headers.
-      if (!llvm::StringSwitch<bool>(llvm::sys::path::extension(Dir->path()))
+      if (!llvm::StringSwitch<bool>(llvm::sys::path::extension(Dir->getName()))
           .Cases(".h", ".H", ".hh", ".hpp", true)
           .Default(false))
         continue;
 
-      const FileEntry *Header = FileMgr.getFile(Dir->path());
+      const FileEntry *Header = FileMgr.getFile(Dir->getName());
       // FIXME: This shouldn't happen unless there is a file system race. Is
       // that worth diagnosing?
       if (!Header)
@@ -232,7 +233,7 @@
 
       // Compute the relative path from the directory to this file.
       SmallVector<StringRef, 16> Components;
-      auto PathIt = llvm::sys::path::rbegin(Dir->path());
+      auto PathIt = llvm::sys::path::rbegin(Dir->getName());
       for (int I = 0; I != Dir.level() + 1; ++I, ++PathIt)
         Components.push_back(*PathIt);
       SmallString<128> RelativeHeader(UmbrellaDir.NameAsWritten);
Index: lib/Lex/HeaderSearch.cpp
===================================================================
--- lib/Lex/HeaderSearch.cpp
+++ lib/Lex/HeaderSearch.cpp
@@ -1341,19 +1341,20 @@
                                 DirNative);
 
         // Search each of the ".framework" directories to load them as modules.
-        for (llvm::sys::fs::directory_iterator Dir(DirNative, EC), DirEnd;
+        vfs::FileSystem &FS = *FileMgr.getVirtualFileSystem();
+        for (vfs::directory_iterator Dir = FS.dir_begin(DirNative, EC), DirEnd;
              Dir != DirEnd && !EC; Dir.increment(EC)) {
-          if (llvm::sys::path::extension(Dir->path()) != ".framework")
+          if (llvm::sys::path::extension(Dir->getName()) != ".framework")
             continue;
 
           const DirectoryEntry *FrameworkDir =
-              FileMgr.getDirectory(Dir->path());
+              FileMgr.getDirectory(Dir->getName());
           if (!FrameworkDir)
             continue;
 
           // Load this framework module.
-          loadFrameworkModule(llvm::sys::path::stem(Dir->path()), FrameworkDir,
-                              IsSystem);
+          loadFrameworkModule(llvm::sys::path::stem(Dir->getName()),
+                              FrameworkDir, IsSystem);
         }
         continue;
       }
@@ -1408,11 +1409,13 @@
   std::error_code EC;
   SmallString<128> DirNative;
   llvm::sys::path::native(SearchDir.getDir()->getName(), DirNative);
-  for (llvm::sys::fs::directory_iterator Dir(DirNative, EC), DirEnd;
+  vfs::FileSystem &FS = *FileMgr.getVirtualFileSystem();
+  for (vfs::directory_iterator Dir = FS.dir_begin(DirNative, EC), DirEnd;
        Dir != DirEnd && !EC; Dir.increment(EC)) {
-    bool IsFramework = llvm::sys::path::extension(Dir->path()) == ".framework";
+    bool IsFramework =
+        llvm::sys::path::extension(Dir->getName()) == ".framework";
     if (IsFramework == SearchDir.isFramework())
-      loadModuleMapFile(Dir->path(), SearchDir.isSystemHeaderDirectory(),
+      loadModuleMapFile(Dir->getName(), SearchDir.isSystemHeaderDirectory(),
                         SearchDir.isFramework());
   }
 
Index: lib/Lex/ModuleMap.cpp
===================================================================
--- lib/Lex/ModuleMap.cpp
+++ lib/Lex/ModuleMap.cpp
@@ -711,13 +711,15 @@
     = StringRef(FrameworkDir->getName());
   llvm::sys::path::append(SubframeworksDirName, "Frameworks");
   llvm::sys::path::native(SubframeworksDirName);
-  for (llvm::sys::fs::directory_iterator Dir(SubframeworksDirName, EC), DirEnd;
+  vfs::FileSystem &FS = *FileMgr.getVirtualFileSystem();
+  for (vfs::directory_iterator Dir = FS.dir_begin(SubframeworksDirName, EC),
+                               DirEnd;
        Dir != DirEnd && !EC; Dir.increment(EC)) {
-    if (!StringRef(Dir->path()).endswith(".framework"))
+    if (!StringRef(Dir->getName()).endswith(".framework"))
       continue;
 
-    if (const DirectoryEntry *SubframeworkDir
-          = FileMgr.getDirectory(Dir->path())) {
+    if (const DirectoryEntry *SubframeworkDir =
+            FileMgr.getDirectory(Dir->getName())) {
       // Note: as an egregious but useful hack, we use the real path here and
       // check whether it is actually a subdirectory of the parent directory.
       // This will not be the case if the 'subframework' is actually a symlink
@@ -1931,11 +1933,13 @@
     // uncommonly used Tcl module on Darwin platforms.
     std::error_code EC;
     SmallVector<Module::Header, 6> Headers;
-    for (llvm::sys::fs::recursive_directory_iterator I(Dir->getName(), EC), E;
+    vfs::FileSystem &FS = *SourceMgr.getFileManager().getVirtualFileSystem();
+    for (vfs::recursive_directory_iterator I(FS, Dir->getName(), EC), E;
          I != E && !EC; I.increment(EC)) {
-      if (const FileEntry *FE = SourceMgr.getFileManager().getFile(I->path())) {
+      if (const FileEntry *FE =
+              SourceMgr.getFileManager().getFile(I->getName())) {
 
-        Module::Header Header = {I->path(), FE};
+        Module::Header Header = {I->getName(), FE};
         Headers.push_back(std::move(Header));
       }
     }
Index: test/Modules/crash-vfs-umbrella-frameworks.m
===================================================================
--- test/Modules/crash-vfs-umbrella-frameworks.m
+++ test/Modules/crash-vfs-umbrella-frameworks.m
@@ -40,3 +40,16 @@
 // CHECKYAML-NEXT:          'external-contents': "/[[PATH]]/i/Frameworks/B.framework/Headers/B.h"
 
 @import I;
+
+// Run the reproducer script - regular exit code is enough to test it works. The
+// intent here is to guarantee that the collect umbrella headers into the VFS
+// can be used, testing that vfs::recursive_directory_iterator is used correctly
+// Make sure to erase the include paths used to build the modules to guarantee
+// that the VFS overlay won't fallback to use it. Also wipe out the module cache
+// to force header search.
+//
+// RUN: cd %t
+// RUN: rm -rf i
+// RUN: rm -rf crash-vfs-umbrella-*.cache/modules/*
+// RUN: chmod 755 crash-vfs-*.sh
+// RUN: ./crash-vfs-*.sh