Index: llvm/include/llvm/Transforms/IPO/ThinLTOBitcodeWriter.h
===================================================================
--- /dev/null
+++ llvm/include/llvm/Transforms/IPO/ThinLTOBitcodeWriter.h
@@ -0,0 +1,41 @@
+//===- ThinLTOBitcodeWriter.h - Bitcode writing pass for ThinLTO ----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass prepares a module containing type metadata for ThinLTO by splitting
+// it into regular and thin LTO parts if possible, and writing both parts to
+// a multi-module bitcode file. Modules that do not contain type metadata are
+// written unmodified as a single module.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_IPO_THINLTOBITCODEWRITER_H
+#define LLVM_TRANSFORMS_IPO_THINLTOBITCODEWRITER_H
+
+#include <llvm/IR/PassManager.h>
+#include <llvm/Support/raw_ostream.h>
+
+namespace llvm {
+
+class ThinLTOBitcodeWriterPass
+    : public PassInfoMixin<ThinLTOBitcodeWriterPass> {
+  raw_ostream &OS;
+  raw_ostream *ThinLinkOS;
+
+public:
+  // Writes bitcode to OS. Also write thin link file to ThinLinkOS, if
+  // it's not nullptr.
+  ThinLTOBitcodeWriterPass(raw_ostream &OS, raw_ostream *ThinLinkOS)
+      : OS(OS), ThinLinkOS(ThinLinkOS) {}
+
+  PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
+};
+
+} // namespace llvm
+
+#endif
Index: llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp
===================================================================
--- llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp
+++ llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp
@@ -6,14 +6,8 @@
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
-//
-// This pass prepares a module containing type metadata for ThinLTO by splitting
-// it into regular and thin LTO parts if possible, and writing both parts to
-// a multi-module bitcode file. Modules that do not contain type metadata are
-// written unmodified as a single module.
-//
-//===----------------------------------------------------------------------===//
 
+#include "llvm/Transforms/IPO/ThinLTOBitcodeWriter.h"
 #include "llvm/Analysis/BasicAliasAnalysis.h"
 #include "llvm/Analysis/ModuleSummaryAnalysis.h"
 #include "llvm/Analysis/ProfileSummaryInfo.h"
@@ -436,3 +430,15 @@
                                                 raw_ostream *ThinLinkOS) {
   return new WriteThinLTOBitcode(Str, ThinLinkOS);
 }
+
+PreservedAnalyses
+llvm::ThinLTOBitcodeWriterPass::run(Module &M, ModuleAnalysisManager &AM) {
+  FunctionAnalysisManager &FAM =
+      AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
+  writeThinLTOBitcode(OS, ThinLinkOS,
+                      [&FAM](Function &F) -> AAResults & {
+                        return FAM.getResult<AAManager>(F);
+                      },
+                      M, &AM.getResult<ModuleSummaryIndexAnalysis>(M));
+  return PreservedAnalyses::all();
+}
Index: llvm/test/Transforms/ThinLTOBitcodeWriter/new-pm.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/ThinLTOBitcodeWriter/new-pm.ll
@@ -0,0 +1,9 @@
+; RUN: opt -passes='no-op-module' -debug-pass-manager -thinlto-bc -thin-link-bitcode-file=%t2 -o %t %s 2>&1 | FileCheck %s --check-prefix=DEBUG_PM
+; RUN: llvm-bcanalyzer -dump %t2 | FileCheck %s --check-prefix=BITCODE
+
+; DEBUG_PM: ThinLTOBitcodeWriterPass
+; BITCODE: Foo
+
+define void @Foo() {
+  ret void
+}
Index: llvm/tools/opt/NewPMDriver.h
===================================================================
--- llvm/tools/opt/NewPMDriver.h
+++ llvm/tools/opt/NewPMDriver.h
@@ -21,6 +21,8 @@
 #ifndef LLVM_TOOLS_OPT_NEWPMDRIVER_H
 #define LLVM_TOOLS_OPT_NEWPMDRIVER_H
 
+#include <llvm/ADT/Optional.h>
+
 namespace llvm {
 class StringRef;
 class LLVMContext;
@@ -47,13 +49,16 @@
 /// inclusion of the new pass manager headers and the old headers into the same
 /// file. It's interface is consequentially somewhat ad-hoc, but will go away
 /// when the transition finishes.
-bool runPassPipeline(StringRef Arg0, Module &M,
-                     TargetMachine *TM, tool_output_file *Out,
-                     StringRef PassPipeline, opt_tool::OutputKind OK,
-                     opt_tool::VerifierKind VK,
+///
+/// ThinLTOBC indicates whether to use ThinLTO's bitcode writer, and if so,
+/// the *nullable* pointer points to the opened link file.
+bool runPassPipeline(StringRef Arg0, Module &M, TargetMachine *TM,
+                     tool_output_file *Out, StringRef PassPipeline,
+                     opt_tool::OutputKind OK, opt_tool::VerifierKind VK,
                      bool ShouldPreserveAssemblyUseListOrder,
                      bool ShouldPreserveBitcodeUseListOrder,
-                     bool EmitSummaryIndex, bool EmitModuleHash);
+                     bool EmitSummaryIndex, bool EmitModuleHash,
+                     Optional<tool_output_file *> ThinLTOBC);
 }
 
 #endif
Index: llvm/tools/opt/NewPMDriver.cpp
===================================================================
--- llvm/tools/opt/NewPMDriver.cpp
+++ llvm/tools/opt/NewPMDriver.cpp
@@ -29,6 +29,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/ToolOutputFile.h"
 #include "llvm/Target/TargetMachine.h"
+#include "llvm/Transforms/IPO/ThinLTOBitcodeWriter.h"
 #include "llvm/Transforms/Scalar/LoopPassManager.h"
 
 using namespace llvm;
@@ -47,13 +48,13 @@
                         "pipeline for handling managed aliasing queries"),
                cl::Hidden);
 
-bool llvm::runPassPipeline(StringRef Arg0, Module &M,
-                           TargetMachine *TM, tool_output_file *Out,
-                           StringRef PassPipeline, OutputKind OK,
-                           VerifierKind VK,
+bool llvm::runPassPipeline(StringRef Arg0, Module &M, TargetMachine *TM,
+                           tool_output_file *Out, StringRef PassPipeline,
+                           OutputKind OK, VerifierKind VK,
                            bool ShouldPreserveAssemblyUseListOrder,
                            bool ShouldPreserveBitcodeUseListOrder,
-                           bool EmitSummaryIndex, bool EmitModuleHash) {
+                           bool EmitSummaryIndex, bool EmitModuleHash,
+                           Optional<tool_output_file *> ThinLTOBC) {
   PassBuilder PB(TM);
 
   // Specially handle the alias analysis manager so that we can register
@@ -101,8 +102,13 @@
         PrintModulePass(Out->os(), "", ShouldPreserveAssemblyUseListOrder));
     break;
   case OK_OutputBitcode:
-    MPM.addPass(BitcodeWriterPass(Out->os(), ShouldPreserveBitcodeUseListOrder,
-                                  EmitSummaryIndex, EmitModuleHash));
+    if (ThinLTOBC)
+      MPM.addPass(ThinLTOBitcodeWriterPass(
+          Out->os(), *ThinLTOBC ? &(*ThinLTOBC)->os() : nullptr));
+    else
+      MPM.addPass(BitcodeWriterPass(Out->os(),
+                                    ShouldPreserveBitcodeUseListOrder,
+                                    EmitSummaryIndex, EmitModuleHash));
     break;
   }
 
@@ -113,7 +119,10 @@
   MPM.run(M, MAM);
 
   // Declare success.
-  if (OK != OK_NoOutput)
+  if (OK != OK_NoOutput) {
     Out->keep();
+    if (ThinLTOBC && *ThinLTOBC)
+      (*ThinLTOBC)->keep();
+  }
   return true;
 }
Index: llvm/tools/opt/opt.cpp
===================================================================
--- llvm/tools/opt/opt.cpp
+++ llvm/tools/opt/opt.cpp
@@ -529,10 +529,13 @@
     // The user has asked to use the new pass manager and provided a pipeline
     // string. Hand off the rest of the functionality to the new code for that
     // layer.
-    return runPassPipeline(argv[0], *M, TM.get(), Out.get(),
-                           PassPipeline, OK, VK, PreserveAssemblyUseListOrder,
+    Optional<tool_output_file *> ThinLTOBC;
+    if (OutputThinLTOBC)
+      ThinLTOBC = ThinLinkOut.get();
+    return runPassPipeline(argv[0], *M, TM.get(), Out.get(), PassPipeline, OK,
+                           VK, PreserveAssemblyUseListOrder,
                            PreserveBitcodeUseListOrder, EmitSummaryIndex,
-                           EmitModuleHash)
+                           EmitModuleHash, ThinLTOBC)
                ? 0
                : 1;
   }