diff --git a/src/llvm-project/clang/lib/Basic/FileManager.cpp b/src/llvm-project/clang/lib/Basic/FileManager.cpp
index e92e9d5..6e9d5d7 100644
--- a/src/llvm-project/clang/lib/Basic/FileManager.cpp
+++ b/src/llvm-project/clang/lib/Basic/FileManager.cpp
@@ -69,21 +69,22 @@
 
 /// Retrieve the directory that the given file name resides in.
 /// Filename can point to either a real file or a virtual file.
-static llvm::ErrorOr<const DirectoryEntry *>
+static llvm::Expected<DirectoryEntryRef>
 getDirectoryFromFile(FileManager &FileMgr, StringRef Filename,
                      bool CacheFailure) {
   if (Filename.empty())
-    return std::errc::no_such_file_or_directory;
+    return llvm::errorCodeToError(
+        make_error_code(std::errc::no_such_file_or_directory));
 
   if (llvm::sys::path::is_separator(Filename[Filename.size() - 1]))
-    return std::errc::is_a_directory;
+    return llvm::errorCodeToError(make_error_code(std::errc::is_a_directory));
 
   StringRef DirName = llvm::sys::path::parent_path(Filename);
   // Use the current directory if file has no path component.
   if (DirName.empty())
     DirName = ".";
 
-  return FileMgr.getDirectory(DirName, CacheFailure);
+  return FileMgr.getDirectoryRef(DirName, CacheFailure);
 }
 
 /// Add all ancestors of the given path (pointing to either a file or
@@ -141,7 +142,7 @@
       SeenDirEntries.insert({DirName, std::errc::no_such_file_or_directory});
   if (!SeenDirInsertResult.second) {
     if (SeenDirInsertResult.first->second)
-      return DirectoryEntryRef(&*SeenDirInsertResult.first);
+      return DirectoryEntryRef(*SeenDirInsertResult.first);
     return llvm::errorCodeToError(SeenDirInsertResult.first->second.getError());
   }
 
@@ -180,7 +181,7 @@
     UDE.Name  = InterndDirName;
   }
 
-  return DirectoryEntryRef(&NamedDirEnt);
+  return DirectoryEntryRef(NamedDirEnt);
 }
 
 llvm::ErrorOr<const DirectoryEntry *>
@@ -212,11 +213,11 @@
           SeenFileInsertResult.first->second.getError());
     // Construct and return and FileEntryRef, unless it's a redirect to another
     // filename.
-    SeenFileEntryOrRedirect Value = *SeenFileInsertResult.first->second;
-    FileEntry *FE;
-    if (LLVM_LIKELY(FE = Value.dyn_cast<FileEntry *>()))
-      return FileEntryRef(SeenFileInsertResult.first->first(), *FE);
-    return getFileRef(*Value.get<const StringRef *>(), openFile, CacheFailure);
+    FileEntryRef::MapValue Value = *SeenFileInsertResult.first->second;
+    if (LLVM_LIKELY(Value.V.is<FileEntry *>()))
+      return FileEntryRef(*SeenFileInsertResult.first);
+    return FileEntryRef(*reinterpret_cast<const FileEntryRef::MapEntry *>(
+        Value.V.get<const void *>()));
   }
 
   // We've not seen this before. Fill it in.
@@ -235,14 +236,15 @@
   // without a 'sys' subdir will get a cached failure result.
   auto DirInfoOrErr = getDirectoryFromFile(*this, Filename, CacheFailure);
   if (!DirInfoOrErr) { // Directory doesn't exist, file can't exist.
+    std::error_code Err = errorToErrorCode(DirInfoOrErr.takeError());
     if (CacheFailure)
-      NamedFileEnt->second = DirInfoOrErr.getError();
+      NamedFileEnt->second = Err;
     else
       SeenFileEntries.erase(Filename);
 
-    return llvm::errorCodeToError(DirInfoOrErr.getError());
+    return llvm::errorCodeToError(Err);
   }
-  const DirectoryEntry *DirInfo = *DirInfoOrErr;
+  DirectoryEntryRef DirInfo = *DirInfoOrErr;
 
   // FIXME: Use the directory info to prune this, before doing the stat syscall.
   // FIXME: This will reduce the # syscalls.
@@ -268,26 +270,30 @@
   // This occurs when one dir is symlinked to another, for example.
   FileEntry &UFE = UniqueRealFiles[Status.getUniqueID()];
 
-  NamedFileEnt->second = &UFE;
-
-  // If the name returned by getStatValue is different than Filename, re-intern
-  // the name.
-  if (Status.getName() != Filename) {
-    auto &NewNamedFileEnt =
-        *SeenFileEntries.insert({Status.getName(), &UFE}).first;
-    assert((*NewNamedFileEnt.second).get<FileEntry *>() == &UFE &&
+  if (Status.getName() == Filename) {
+    // The name matches. Set the FileEntry.
+    NamedFileEnt->second = FileEntryRef::MapValue(UFE, DirInfo);
+  } else {
+    // Name mismatch. We need a redirect. First grab the actual entry we want
+    // to return.
+    auto &Redirection =
+        *SeenFileEntries
+             .insert({Status.getName(), FileEntryRef::MapValue(UFE, DirInfo)})
+             .first;
+    assert(Redirection.second->V.is<FileEntry *>() &&
+           "filename redirected to a non-canonical filename?");
+    assert(Redirection.second->V.get<FileEntry *>() == &UFE &&
            "filename from getStatValue() refers to wrong file");
-    InterndFileName = NewNamedFileEnt.first().data();
-    // In addition to re-interning the name, construct a redirecting seen file
-    // entry, that will point to the name the filesystem actually wants to use.
-    StringRef *Redirect = new (CanonicalNameStorage) StringRef(InterndFileName);
-    auto SeenFileInsertResultIt = SeenFileEntries.find(Filename);
-    assert(SeenFileInsertResultIt != SeenFileEntries.end() &&
-           "unexpected SeenFileEntries cache miss");
-    SeenFileInsertResultIt->second = Redirect;
-    NamedFileEnt = &*SeenFileInsertResultIt;
+
+    // Cache the redirection in the previously-inserted entry, still available
+    // in the tentative return value.
+    NamedFileEnt->second = FileEntryRef::MapValue(Redirection);
+
+    // Fix the tentative return value.
+    NamedFileEnt = &Redirection;
   }
 
+  FileEntryRef ReturnedRef(*NamedFileEnt);
   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
@@ -296,26 +302,26 @@
     // module's structure when its headers/module map are mapped in the VFS.
     // We should remove this as soon as we can properly support a file having
     // multiple names.
-    if (DirInfo != UFE.Dir && Status.IsVFSMapped)
-      UFE.Dir = DirInfo;
+    if (&DirInfo.getDirEntry() != UFE.Dir && Status.IsVFSMapped)
+      UFE.Dir = &DirInfo.getDirEntry();
 
-    // Always update the name to use the last name by which a file was accessed.
-    // FIXME: Neither this nor always using the first name is correct; we want
-    // to switch towards a design where we return a FileName object that
+    // Always update LastRef to the last name by which a file was accessed.
+    // FIXME: Neither this nor always using the first reference is correct; we
+    // want to switch towards a design where we return a FileName object that
     // encapsulates both the name by which the file was accessed and the
     // corresponding FileEntry.
-    // FIXME: The Name should be removed from FileEntry once all clients
-    // adopt FileEntryRef.
-    UFE.Name = InterndFileName;
+    // FIXME: LastRef should be removed from FileEntry once all clients adopt
+    // FileEntryRef.
+    UFE.LastRef = ReturnedRef;
 
-    return FileEntryRef(InterndFileName, UFE);
+    return ReturnedRef;
   }
 
   // Otherwise, we don't have this file yet, add it.
-  UFE.Name    = InterndFileName;
+  UFE.LastRef = ReturnedRef;
   UFE.Size    = Status.getSize();
   UFE.ModTime = llvm::sys::toTimeT(Status.getLastModificationTime());
-  UFE.Dir     = DirInfo;
+  UFE.Dir     = &DirInfo.getDirEntry();
   UFE.UID     = NextFileUID++;
   UFE.UniqueID = Status.getUniqueID();
   UFE.IsNamedPipe = Status.getType() == llvm::sys::fs::file_type::fifo_file;
@@ -329,24 +335,46 @@
     // We should still fill the path even if we aren't opening the file.
     fillRealPathName(&UFE, InterndFileName);
   }
-  return FileEntryRef(InterndFileName, UFE);
+  return ReturnedRef;
 }
 
-const FileEntry *
-FileManager::getVirtualFile(StringRef Filename, off_t Size,
-                            time_t ModificationTime) {
+llvm::Expected<FileEntryRef> FileManager::getSTDIN() {
+  // Only read stdin once.
+  if (STDIN)
+    return *STDIN;
+
+  std::unique_ptr<llvm::MemoryBuffer> Content;
+  if (auto ContentOrError = llvm::MemoryBuffer::getSTDIN())
+    Content = std::move(*ContentOrError);
+  else
+    return llvm::errorCodeToError(ContentOrError.getError());
+
+  STDIN = getVirtualFileRef(Content->getBufferIdentifier(),
+                            Content->getBufferSize(), 0);
+  FileEntry &FE = const_cast<FileEntry &>(STDIN->getFileEntry());
+  FE.Content = std::move(Content);
+  FE.IsNamedPipe = true;
+  return *STDIN;
+}
+
+const FileEntry *FileManager::getVirtualFile(StringRef Filename, off_t Size,
+                                             time_t ModificationTime) {
+  return &getVirtualFileRef(Filename, Size, ModificationTime).getFileEntry();
+}
+
+FileEntryRef FileManager::getVirtualFileRef(StringRef Filename, off_t Size,
+                                            time_t ModificationTime) {
   ++NumFileLookups;
 
   // See if there is already an entry in the map for an existing file.
   auto &NamedFileEnt = *SeenFileEntries.insert(
       {Filename, std::errc::no_such_file_or_directory}).first;
   if (NamedFileEnt.second) {
-    SeenFileEntryOrRedirect Value = *NamedFileEnt.second;
-    FileEntry *FE;
-    if (LLVM_LIKELY(FE = Value.dyn_cast<FileEntry *>()))
-      return FE;
-    return getVirtualFile(*Value.get<const StringRef *>(), Size,
-                          ModificationTime);
+    FileEntryRef::MapValue Value = *NamedFileEnt.second;
+    if (LLVM_LIKELY(Value.V.is<FileEntry *>()))
+      return FileEntryRef(NamedFileEnt);
+    return FileEntryRef(*reinterpret_cast<const FileEntryRef::MapEntry *>(
+        Value.V.get<const void *>()));
   }
 
   // We've not seen this before, or the file is cached as non-existent.
@@ -357,7 +385,8 @@
   // Now that all ancestors of Filename are in the cache, the
   // following call is guaranteed to find the DirectoryEntry from the
   // cache.
-  auto DirInfo = getDirectoryFromFile(*this, Filename, /*CacheFailure=*/true);
+  auto DirInfo = expectedToOptional(
+      getDirectoryFromFile(*this, Filename, /*CacheFailure=*/true));
   assert(DirInfo &&
          "The directory of a virtual file should already be in the cache.");
 
@@ -372,7 +401,7 @@
       Status.getUser(), Status.getGroup(), Size,
       Status.getType(), Status.getPermissions());
 
-    NamedFileEnt.second = UFE;
+    NamedFileEnt.second = FileEntryRef::MapValue(*UFE, *DirInfo);
 
     // If we had already opened this file, close it now so we don't
     // leak the descriptor. We're not going to use the file
@@ -381,8 +410,11 @@
       UFE->closeFile();
 
     // If we already have an entry with this inode, return it.
+    //
+    // FIXME: Surely this should add a reference by the new name, and return
+    // it instead...
     if (UFE->isValid())
-      return UFE;
+      return FileEntryRef(NamedFileEnt);
 
     UFE->UniqueID = Status.getUniqueID();
     UFE->IsNamedPipe = Status.getType() == llvm::sys::fs::file_type::fifo_file;
@@ -390,17 +422,17 @@
   } else {
     VirtualFileEntries.push_back(std::make_unique<FileEntry>());
     UFE = VirtualFileEntries.back().get();
-    NamedFileEnt.second = UFE;
+    NamedFileEnt.second = FileEntryRef::MapValue(*UFE, *DirInfo);
   }
 
-  UFE->Name    = InterndFileName;
+  UFE->LastRef = FileEntryRef(NamedFileEnt);
   UFE->Size    = Size;
   UFE->ModTime = ModificationTime;
-  UFE->Dir     = *DirInfo;
+  UFE->Dir     = &DirInfo->getDirEntry();
   UFE->UID     = NextFileUID++;
   UFE->IsValid = true;
   UFE->File.reset();
-  return UFE;
+  return FileEntryRef(NamedFileEnt);
 }
 
 llvm::Optional<FileEntryRef> FileManager::getBypassFile(FileEntryRef VF) {
@@ -409,17 +441,30 @@
   if (getStatValue(VF.getName(), Status, /*isFile=*/true, /*F=*/nullptr))
     return None;
 
-  // Fill it in from the stat.
+  if (!SeenBypassFileEntries)
+    SeenBypassFileEntries = std::make_unique<
+        llvm::StringMap<llvm::ErrorOr<FileEntryRef::MapValue>>>();
+
+  // If we've already bypassed just use the existing one.
+  auto Insertion = SeenBypassFileEntries->insert(
+      {VF.getName(), std::errc::no_such_file_or_directory});
+  if (!Insertion.second)
+    return FileEntryRef(*Insertion.first);
+
+  // Fill in the new entry from the stat.
   BypassFileEntries.push_back(std::make_unique<FileEntry>());
   const FileEntry &VFE = VF.getFileEntry();
   FileEntry &BFE = *BypassFileEntries.back();
-  BFE.Name = VFE.getName();
+  Insertion.first->second = FileEntryRef::MapValue(BFE, VF.getDir());
+  BFE.LastRef = FileEntryRef(*Insertion.first);
   BFE.Size = Status.getSize();
   BFE.Dir = VFE.Dir;
   BFE.ModTime = llvm::sys::toTimeT(Status.getLastModificationTime());
   BFE.UID = NextFileUID++;
   BFE.IsValid = true;
-  return FileEntryRef(VF.getName(), BFE);
+
+  // Save the entry in the bypass table and return.
+  return FileEntryRef(*Insertion.first);
 }
 
 bool FileManager::FixupRelativePath(SmallVectorImpl<char> &path) const {
@@ -460,10 +505,14 @@
 llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
 FileManager::getBufferForFile(const FileEntry *Entry, bool isVolatile,
                               bool RequiresNullTerminator) {
+  // If the content is living on the file entry, return a reference to it.
+  if (Entry->Content)
+    return llvm::MemoryBuffer::getMemBuffer(Entry->Content->getMemBufferRef());
+
   uint64_t FileSize = Entry->getSize();
   // If there's a high enough chance that the file have changed since we
   // got its size, force a stat before opening it.
-  if (isVolatile)
+  if (isVolatile || Entry->isNamedPipe())
     FileSize = -1;
 
   StringRef Filename = Entry->getName();
@@ -534,13 +583,13 @@
   UIDToFiles.resize(NextFileUID);
 
   // Map file entries
-  for (llvm::StringMap<llvm::ErrorOr<SeenFileEntryOrRedirect>,
+  for (llvm::StringMap<llvm::ErrorOr<FileEntryRef::MapValue>,
                        llvm::BumpPtrAllocator>::const_iterator
            FE = SeenFileEntries.begin(),
            FEEnd = SeenFileEntries.end();
        FE != FEEnd; ++FE)
-    if (llvm::ErrorOr<SeenFileEntryOrRedirect> Entry = FE->getValue()) {
-      if (const auto *FE = (*Entry).dyn_cast<FileEntry *>())
+    if (llvm::ErrorOr<FileEntryRef::MapValue> Entry = FE->getValue()) {
+      if (const auto *FE = Entry->V.dyn_cast<FileEntry *>())
         UIDToFiles[FE->getUID()] = FE;
     }