--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lld/ELF/LTO.h	Thu Feb 13 15:10:13 2020 +0900
@@ -0,0 +1,62 @@
+//===- LTO.h ----------------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides a way to combine bitcode files into one ELF
+// file by compiling them using LLVM.
+//
+// If LTO is in use, your input files are not in regular ELF files
+// but instead LLVM bitcode files. In that case, the linker has to
+// convert bitcode files into the native format so that we can create
+// an ELF file that contains native code. This file provides that
+// functionality.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLD_ELF_LTO_H
+#define LLD_ELF_LTO_H
+
+#include "lld/Common/LLVM.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/Support/raw_ostream.h"
+#include <memory>
+#include <vector>
+
+namespace llvm {
+namespace lto {
+class LTO;
+}
+} // namespace llvm
+
+namespace lld {
+namespace elf {
+
+class BitcodeFile;
+class InputFile;
+class LazyObjFile;
+
+class BitcodeCompiler {
+public:
+  BitcodeCompiler();
+  ~BitcodeCompiler();
+
+  void add(BitcodeFile &f);
+  std::vector<InputFile *> compile();
+
+private:
+  std::unique_ptr<llvm::lto::LTO> ltoObj;
+  std::vector<SmallString<0>> buf;
+  std::vector<std::unique_ptr<MemoryBuffer>> files;
+  llvm::DenseSet<StringRef> usedStartStop;
+  std::unique_ptr<llvm::raw_fd_ostream> indexFile;
+  llvm::DenseSet<StringRef> thinIndices;
+};
+} // namespace elf
+} // namespace lld
+
+#endif