Import prebuilt clang toolchain for linux.
diff --git a/linux-x64/clang/include/llvm/LTO/Caching.h b/linux-x64/clang/include/llvm/LTO/Caching.h
new file mode 100644
index 0000000..7201ab3
--- /dev/null
+++ b/linux-x64/clang/include/llvm/LTO/Caching.h
@@ -0,0 +1,40 @@
+//===- Caching.h - LLVM Link Time Optimizer Configuration -----------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the localCache function, which allows clients to add a
+// filesystem cache to ThinLTO.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LTO_CACHING_H
+#define LLVM_LTO_CACHING_H
+
+#include "llvm/LTO/LTO.h"
+#include <string>
+
+namespace llvm {
+namespace lto {
+
+/// This type defines the callback to add a pre-existing native object file
+/// (e.g. in a cache).
+///
+/// Buffer callbacks must be thread safe.
+typedef std::function<void(unsigned Task, std::unique_ptr<MemoryBuffer> MB)>
+ AddBufferFn;
+
+/// Create a local file system cache which uses the given cache directory and
+/// file callback. This function also creates the cache directory if it does not
+/// already exist.
+Expected<NativeObjectCache> localCache(StringRef CacheDirectoryPath,
+ AddBufferFn AddBuffer);
+
+} // namespace lto
+} // namespace llvm
+
+#endif