Index: llvm/include/llvm-c/BitWriter.h
===================================================================
--- llvm/include/llvm-c/BitWriter.h
+++ llvm/include/llvm-c/BitWriter.h
@@ -47,6 +47,9 @@
 /** Writes a module to a new memory buffer and returns it. */
 LLVMMemoryBufferRef LLVMWriteBitcodeToMemoryBuffer(LLVMModuleRef M);
 
+/** Writes a module with ThinLTO summary to a new memory buffer and returns it. */
+LLVMMemoryBufferRef LLVMWriteThinLTOBitcodeToMemoryBuffer(LLVMModuleRef M);
+
 /**
  * @}
  */
Index: llvm/lib/Bitcode/Writer/BitWriter.cpp
===================================================================
--- llvm/lib/Bitcode/Writer/BitWriter.cpp
+++ llvm/lib/Bitcode/Writer/BitWriter.cpp
@@ -8,10 +8,12 @@
 
 #include "llvm-c/BitWriter.h"
 #include "llvm/Bitcode/BitcodeWriter.h"
+#include "llvm/IR/LegacyPassManager.h"
 #include "llvm/IR/Module.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/IPO.h"
 using namespace llvm;
 
 
@@ -47,3 +49,12 @@
   WriteBitcodeToFile(*unwrap(M), OS);
   return wrap(MemoryBuffer::getMemBufferCopy(OS.str()).release());
 }
+
+LLVMMemoryBufferRef LLVMWriteThinLTOBitcodeToMemoryBuffer(LLVMModuleRef M) {
+  std::string Data;
+  llvm::raw_string_ostream OS(Data);
+  llvm::legacy::PassManager PM;
+  PM.add(createWriteThinLTOBitcodePass(OS));
+  PM.run(*llvm::unwrap(M));
+  return llvm::wrap(llvm::MemoryBuffer::getMemBufferCopy(OS.str()).release());
+}