Index: include/clang/Basic/FileManager.h
===================================================================
--- include/clang/Basic/FileManager.h
+++ include/clang/Basic/FileManager.h
@@ -69,15 +69,14 @@
   bool IsNamedPipe;
   bool InPCH;
   bool IsValid;               // Is this \c FileEntry initialized and valid?
-  bool DeferredOpen;          // Created by getFile(OpenFile=0); may open later.
 
   /// The open file, if it is owned by the \p FileEntry.
   mutable std::unique_ptr<llvm::vfs::File> File;
 
 public:
   FileEntry()
-      : UniqueID(0, 0), IsNamedPipe(false), InPCH(false), IsValid(false),
-        DeferredOpen(false) {}
+      : UniqueID(0, 0), IsNamedPipe(false), InPCH(false), IsValid(false)
+  {}
 
   FileEntry(const FileEntry &) = delete;
   FileEntry &operator=(const FileEntry &) = delete;
Index: lib/Basic/FileManager.cpp
===================================================================
--- lib/Basic/FileManager.cpp
+++ lib/Basic/FileManager.cpp
@@ -188,21 +188,15 @@
       *SeenFileEntries.insert(std::make_pair(Filename, nullptr)).first;
 
   // See if there is already an entry in the map.
-  if (NamedFileEnt.second) {
-    if (NamedFileEnt.second == NON_EXISTENT_FILE)
-      return nullptr;
-    // Entry exists: return it *unless* it wasn't opened and open is requested.
-    if (!(NamedFileEnt.second->DeferredOpen && openFile))
-      return NamedFileEnt.second;
-    // We previously stat()ed the file, but didn't open it: do that below.
-    // FIXME: the below does other redundant work too (stats the dir and file).
-  } else {
-    // By default, initialize it to invalid.
-    NamedFileEnt.second = NON_EXISTENT_FILE;
-  }
+  if (NamedFileEnt.second)
+    return NamedFileEnt.second == NON_EXISTENT_FILE ? nullptr
+                                                    : NamedFileEnt.second;
 
   ++NumFileCacheMisses;
 
+  // By default, initialize it to invalid.
+  NamedFileEnt.second = NON_EXISTENT_FILE;
+
   // Get the null-terminated file name as stored as the key of the
   // SeenFileEntries map.
   StringRef InterndFileName = NamedFileEnt.first();
@@ -240,7 +234,6 @@
   // It exists.  See if we have already opened a file with the same inode.
   // This occurs when one dir is symlinked to another, for example.
   FileEntry &UFE = UniqueRealFiles[Data.UniqueID];
-  UFE.DeferredOpen = !openFile;
 
   NamedFileEnt.second = &UFE;
 
@@ -257,15 +250,6 @@
     InterndFileName = NamedFileEnt.first().data();
   }
 
-  // If we opened the file for the first time, record the resulting info.
-  // Do this even if the cache entry was valid, maybe we didn't previously open.
-  if (F && !UFE.File) {
-    if (auto PathName = F->getName())
-      fillRealPathName(&UFE, *PathName);
-    UFE.File = std::move(F);
-    assert(!UFE.DeferredOpen && "we just opened it!");
-  }
-
   if (UFE.isValid()) { // Already have an entry with this inode, return it.
 
     // FIXME: this hack ensures that if we look up a file by a virtual path in
@@ -296,9 +280,13 @@
   UFE.UniqueID = Data.UniqueID;
   UFE.IsNamedPipe = Data.IsNamedPipe;
   UFE.InPCH = Data.InPCH;
+  UFE.File = std::move(F);
   UFE.IsValid = true;
-  // Note File and DeferredOpen were initialized above.
 
+  if (UFE.File) {
+    if (auto PathName = UFE.File->getName())
+      fillRealPathName(&UFE, *PathName);
+  }
   return &UFE;
 }
 
@@ -370,7 +358,6 @@
   UFE->UID     = NextFileUID++;
   UFE->IsValid = true;
   UFE->File.reset();
-  UFE->DeferredOpen = false;
   return UFE;
 }
 
Index: test/PCH/leakfiles
===================================================================
--- /dev/null
+++ test/PCH/leakfiles
@@ -0,0 +1,29 @@
+// Test that compiling using a PCH doesn't leak file descriptors.
+// https://bugs.chromium.org/p/chromium/issues/detail?id=924225
+//
+// This test requires bash loops and ulimit.
+// REQUIRES: shell
+// UNSUPPORTED: win32
+//
+// Set up source files. lib/lib.h includes lots of lib*.h files in that dir.
+// client.c includes lib/lib.h, and also the individual files directly.
+//
+// RUN: rm -rf %t
+// RUN: mkdir %t
+// RUN: cd %t
+// RUN: mkdir lib
+// RUN: for i in {1..300}; do touch lib/lib$i.h; done
+// RUN: for i in {1..300}; do echo "#include \"lib$i.h\"" >> lib/lib.h; done
+// RUN: echo "#include \"lib/lib.h\"" > client.c
+// RUN: for i in {1..300}; do echo "#include \"lib/lib$i.h\"" >> client.c; done
+//
+// We want to verify that we don't hold all the files open at the same time.
+// This is important e.g. on mac, which has a low default FD limit.
+// RUN: ulimit -n 100
+//
+// Test without PCH.
+// RUN: %clang_cc1 -fsyntax-only -Ilib/ client.c
+//
+// Test with PCH.
+// RUN: %clang_cc1 -emit-pch -o pch -Ilib/ client.c
+// RUN: %clang_cc1 -include-pch pch -Ilib/ client.c -fsyntax-only
Index: unittests/Basic/FileManagerTest.cpp
===================================================================
--- unittests/Basic/FileManagerTest.cpp
+++ unittests/Basic/FileManagerTest.cpp
@@ -221,33 +221,6 @@
   EXPECT_EQ(nullptr, file);
 }
 
-// When calling getFile(OpenFile=false); getFile(OpenFile=true) the file is
-// opened for the second call.
-TEST_F(FileManagerTest, getFileDefersOpen) {
-  llvm::IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem> FS(
-      new llvm::vfs::InMemoryFileSystem());
-  FS->addFile("/tmp/test", 0, llvm::MemoryBuffer::getMemBufferCopy("test"));
-  FS->addFile("/tmp/testv", 0, llvm::MemoryBuffer::getMemBufferCopy("testv"));
-  FileManager manager(options, FS);
-
-  const FileEntry *file = manager.getFile("/tmp/test", /*OpenFile=*/false);
-  ASSERT_TRUE(file != nullptr);
-  ASSERT_TRUE(file->isValid());
-  // "real path name" reveals whether the file was actually opened.
-  EXPECT_FALSE(file->isOpenForTests());
-
-  file = manager.getFile("/tmp/test", /*OpenFile=*/true);
-  ASSERT_TRUE(file != nullptr);
-  ASSERT_TRUE(file->isValid());
-  EXPECT_TRUE(file->isOpenForTests());
-
-  // However we should never try to open a file previously opened as virtual.
-  ASSERT_TRUE(manager.getVirtualFile("/tmp/testv", 5, 0));
-  ASSERT_TRUE(manager.getFile("/tmp/testv", /*OpenFile=*/false));
-  file = manager.getFile("/tmp/testv", /*OpenFile=*/true);
-  EXPECT_FALSE(file->isOpenForTests());
-}
-
 // The following tests apply to Unix-like system only.
 
 #ifndef _WIN32