Index: include/llvm/LTO/Config.h
===================================================================
--- include/llvm/LTO/Config.h
+++ include/llvm/LTO/Config.h
@@ -78,6 +78,11 @@
   /// Disable entirely the optimizer, including importing for ThinLTO
   bool CodeGenOnly = false;
 
+  /// If this field is set, the set of passes run in the middle-end optimizer
+  /// will be the one specified by the string. Only works with the new pass
+  /// manager as the old one doesn't have this ability.
+  std::string OptPipeline;
+
   /// Setting this field will replace target triples in input files with this
   /// triple.
   std::string OverrideTriple;
@@ -164,6 +169,7 @@
         RelocModel(std::move(X.RelocModel)), CodeModel(std::move(X.CodeModel)),
         CGOptLevel(std::move(X.CGOptLevel)), OptLevel(std::move(X.OptLevel)),
         DisableVerify(std::move(X.DisableVerify)),
+        OptPipeline(std::move(X.OptPipeline)),
         OverrideTriple(std::move(X.OverrideTriple)),
         DefaultTriple(std::move(X.DefaultTriple)),
         ShouldDiscardValueNames(std::move(X.ShouldDiscardValueNames)),
@@ -187,6 +193,7 @@
     CGOptLevel = std::move(X.CGOptLevel);
     OptLevel = std::move(X.OptLevel);
     DisableVerify = std::move(X.DisableVerify);
+    OptPipeline = std::move(X.OptPipeline);
     OverrideTriple = std::move(X.OverrideTriple);
     DefaultTriple = std::move(X.DefaultTriple);
     ShouldDiscardValueNames = std::move(X.ShouldDiscardValueNames);
Index: lib/LTO/LLVMBuild.txt
===================================================================
--- lib/LTO/LLVMBuild.txt
+++ lib/LTO/LLVMBuild.txt
@@ -31,6 +31,7 @@
  MC
  ObjCARC
  Object
+ Passes
  Scalar
  Support
  Target
Index: lib/LTO/LTOBackend.cpp
===================================================================
--- lib/LTO/LTOBackend.cpp
+++ lib/LTO/LTOBackend.cpp
@@ -15,12 +15,18 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/LTO/LTOBackend.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/CGSCCPassManager.h"
+#include "llvm/Analysis/LoopPassManager.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/Bitcode/ReaderWriter.h"
 #include "llvm/IR/LegacyPassManager.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/IR/Verifier.h"
 #include "llvm/LTO/LTO.h"
 #include "llvm/MC/SubtargetFeature.h"
+#include "llvm/Passes/PassBuilder.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/TargetRegistry.h"
@@ -136,10 +142,45 @@
   passes.run(M);
 }
 
+static void runNewPMCustomPasses(Config &C, Module &M, TargetMachine *TM) {
+  PassBuilder PB(TM);
+  AAManager AA;
+  LoopAnalysisManager LAM;
+  FunctionAnalysisManager FAM;
+  CGSCCAnalysisManager CGAM;
+  ModuleAnalysisManager MAM;
+
+  // Register the AA manager first so that our version is the one used.
+  FAM.registerPass([&] { return std::move(AA); });
+
+  // Register all the basic analyses with the managers.
+  PB.registerModuleAnalyses(MAM);
+  PB.registerCGSCCAnalyses(CGAM);
+  PB.registerFunctionAnalyses(FAM);
+  PB.registerLoopAnalyses(LAM);
+  PB.crossRegisterProxies(LAM, FAM, CGAM, MAM);
+
+  ModulePassManager MPM;
+  if (!C.DisableVerify)
+    MPM.addPass(VerifierPass());
+
+  // Now, add all the passes we've been requested to.
+  if (!PB.parsePassPipeline(MPM, C.OptPipeline))
+    report_fatal_error("unable to parse pass pipeline description: " +
+                       C.OptPipeline);
+
+  if (!C.DisableVerify)
+    MPM.addPass(VerifierPass());
+  MPM.run(M, MAM);
+}
+
 bool opt(Config &C, TargetMachine *TM, unsigned Task, Module &M,
          bool IsThinLto) {
   M.setDataLayout(TM->createDataLayout());
-  runOldPMPasses(C, M, TM, IsThinLto);
+  if (C.OptPipeline.empty())
+    runOldPMPasses(C, M, TM, IsThinLto);
+  else
+    runNewPMCustomPasses(C, M, TM);
   if (C.PostOptModuleHook && !C.PostOptModuleHook(Task, M))
     return false;