Index: include/llvm/Passes/PassBuilder.h
===================================================================
--- include/llvm/Passes/PassBuilder.h
+++ include/llvm/Passes/PassBuilder.h
@@ -234,10 +234,14 @@
   /// \p PrepareForThinLTO indicates whether this is invoked in
   /// PrepareForThinLTO phase. Special handling is needed for sample PGO to
   /// ensure profile accurate in the backend profile annotation phase.
+  ///
+  /// \p ThinLTOBackend indicates whether this is invoked in ThinLTOBackend.
+  /// We should not invoke AddDiscriminator pass in the ThinLTOBackend.
   ModulePassManager
   buildModuleSimplificationPipeline(OptimizationLevel Level,
                                     bool DebugLogging = false,
-                                    bool PrepareForThinLTO = false);
+                                    bool PrepareForThinLTO = false,
+                                    bool ThinLTOBackend = false);
 
   /// Construct the core LLVM module optimization pipeline.
   ///
Index: lib/Passes/PassBuilder.cpp
===================================================================
--- lib/Passes/PassBuilder.cpp
+++ lib/Passes/PassBuilder.cpp
@@ -525,7 +525,8 @@
 ModulePassManager
 PassBuilder::buildModuleSimplificationPipeline(OptimizationLevel Level,
                                                bool DebugLogging,
-                                               bool PrepareForThinLTO) {
+                                               bool PrepareForThinLTO,
+                                               bool ThinLTOBackend) {
   ModulePassManager MPM(DebugLogging);
 
   // Do basic inference of function attributes from known properties of system
@@ -535,7 +536,7 @@
   // Create an early function pass manager to cleanup the output of the
   // frontend.
   FunctionPassManager EarlyFPM(DebugLogging);
-  if (PGOOpt && PGOOpt->SamplePGOSupport)
+  if (PGOOpt && PGOOpt->SamplePGOSupport && !ThinLTOBackend)
     EarlyFPM.addPass(AddDiscriminatorsPass());
   EarlyFPM.addPass(SimplifyCFGPass());
   EarlyFPM.addPass(SROA());
@@ -576,16 +577,17 @@
   if (PGOOpt) {
     assert(PGOOpt->RunProfileGen || !PGOOpt->SampleProfileFile.empty() ||
            !PGOOpt->ProfileUseFile.empty() || PGOOpt->SamplePGOSupport);
-    if (PGOOpt->SampleProfileFile.empty())
+    if (!PGOOpt->ProfileGenFile.empty() || !PGOOpt->ProfileUseFile.empty())
       addPGOInstrPasses(MPM, DebugLogging, Level, PGOOpt->RunProfileGen,
                         PGOOpt->ProfileGenFile, PGOOpt->ProfileUseFile);
-    else
+    else if (!PGOOpt->SampleProfileFile.empty())
       MPM.addPass(SampleProfileLoaderPass(PGOOpt->SampleProfileFile));
 
     // Indirect call promotion that promotes intra-module targes only.
     // Do not enable it in PrepareForThinLTO phase during sample PGO because
     // it changes IR to makes profile annotation in back compile inaccurate.
-    if (!PrepareForThinLTO || PGOOpt->SampleProfileFile.empty())
+    if ((!PrepareForThinLTO && !PGOOpt->SampleProfileFile.empty())
+        || !PGOOpt->ProfileUseFile.empty())
       MPM.addPass(PGOIndirectCallPromotion(
           false, PGOOpt && !PGOOpt->SampleProfileFile.empty()));
   }
@@ -781,7 +783,8 @@
 
   // Add the core simplification pipeline.
   MPM.addPass(buildModuleSimplificationPipeline(Level, DebugLogging,
-                                                /*PrepareForThinLTO=*/false));
+                                                /*PrepareForThinLTO=*/false,
+                                                /*ThinLTOBackend=*/false));
 
   // Now add the optimization pipeline.
   MPM.addPass(buildModuleOptimizationPipeline(Level, DebugLogging));
@@ -803,7 +806,8 @@
   // unrolling/vectorization/... now. Just simplify the module as much as we
   // can.
   MPM.addPass(buildModuleSimplificationPipeline(Level, DebugLogging,
-                                                /*PrepareForThinLTO=*/true));
+                                                /*PrepareForThinLTO=*/true,
+                                                /*ThinLTOBackend=*/false));
 
   // Run partial inlining pass to partially inline functions that have
   // large bodies.
@@ -842,7 +846,8 @@
 
   // Add the core simplification pipeline.
   MPM.addPass(buildModuleSimplificationPipeline(Level, DebugLogging,
-                                                /*PrepareForThinLTO=*/false));
+                                                /*PrepareForThinLTO=*/false,
+                                                /*ThinLTOBackend=*/true));
 
   // Now add the optimization pipeline.
   MPM.addPass(buildModuleOptimizationPipeline(Level, DebugLogging));
Index: test/Other/new-pm-thinlto-defaults.ll
===================================================================
--- test/Other/new-pm-thinlto-defaults.ll
+++ test/Other/new-pm-thinlto-defaults.ll
@@ -23,6 +23,9 @@
 ; RUN: opt -disable-verify -debug-pass-manager \
 ; RUN:     -passes='thinlto-pre-link<Oz>,name-anon-globals' -S %s 2>&1 \
 ; RUN:     | FileCheck %s --check-prefixes=CHECK-O,CHECK-Oz,CHECK-PRELINK-O,CHECK-PRELINK-Oz
+; RUN: opt -disable-verify -debug-pass-manager -new-pm-debug-info-for-profiling \
+; RUN:     -passes='thinlto-pre-link<O2>,name-anon-globals' -S  %s 2>&1 \
+; RUN:     | FileCheck %s --check-prefixes=CHECK-DIS,CHECK-O,CHECK-O2,CHECK-PRELINK-O,CHECK-PRELINK-O2
 ;
 ; Postlink pipelines:
 ; RUN: opt -disable-verify -debug-pass-manager \
@@ -40,6 +43,9 @@
 ; RUN: opt -disable-verify -debug-pass-manager \
 ; RUN:     -passes='thinlto<Oz>' -S %s 2>&1 \
 ; RUN:     | FileCheck %s --check-prefixes=CHECK-O,CHECK-Oz,CHECK-POSTLINK-O,CHECK-POSTLINK-Oz
+; RUN: opt -disable-verify -debug-pass-manager -new-pm-debug-info-for-profiling \
+; RUN:     -passes='thinlto<O2>' -S  %s 2>&1 \
+; RUN:     | FileCheck %s --check-prefixes=CHECK-O,CHECK-O2,CHECK-POSTLINK-O,CHECK-POSTLINK-O2
 ;
 ; CHECK-O: Starting llvm::Module pass manager run.
 ; CHECK-O-NEXT: Running pass: PassManager<{{.*}}Module{{.*}}>
@@ -55,6 +61,7 @@
 ; CHECK-O-NEXT: Running pass: ModuleToFunctionPassAdaptor<{{.*}}PassManager{{.*}}>
 ; CHECK-PRELINK-O-NEXT: Running analysis: InnerAnalysisManagerProxy
 ; CHECK-O-NEXT: Starting llvm::Function pass manager run.
+; CHECK-DIS: Running pass: AddDiscriminatorsPass
 ; CHECK-O-NEXT: Running pass: SimplifyCFGPass
 ; CHECK-O-NEXT: Running analysis: TargetIRAnalysis
 ; CHECK-O-NEXT: Running analysis: AssumptionAnalysis