Import prebuilt clang toolchain for linux.
diff --git a/linux-x64/clang/include/lld/Common/Timer.h b/linux-x64/clang/include/lld/Common/Timer.h
new file mode 100644
index 0000000..6654af6
--- /dev/null
+++ b/linux-x64/clang/include/lld/Common/Timer.h
@@ -0,0 +1,59 @@
+//===- Timer.h ----------------------------------------------*- C++ -*-===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLD_COMMON_TIMER_H
+#define LLD_COMMON_TIMER_H
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/StringRef.h"
+#include <assert.h>
+#include <chrono>
+#include <map>
+#include <memory>
+
+namespace lld {
+
+class Timer;
+
+struct ScopedTimer {
+  explicit ScopedTimer(Timer &T);
+
+  ~ScopedTimer();
+
+  void stop();
+
+  Timer *T = nullptr;
+};
+
+class Timer {
+public:
+  Timer(llvm::StringRef Name, Timer &Parent);
+
+  static Timer &root();
+
+  void start();
+  void stop();
+  void print();
+
+  double millis() const;
+
+private:
+  explicit Timer(llvm::StringRef Name);
+  void print(int Depth, double TotalDuration, bool Recurse = true) const;
+
+  std::chrono::time_point<std::chrono::high_resolution_clock> StartTime;
+  std::chrono::nanoseconds Total;
+  std::vector<Timer *> Children;
+  std::string Name;
+  Timer *Parent;
+};
+
+} // namespace lld
+
+#endif