Index: cfe/trunk/include/clang/Driver/CC1Options.td
===================================================================
--- cfe/trunk/include/clang/Driver/CC1Options.td
+++ cfe/trunk/include/clang/Driver/CC1Options.td
@@ -323,6 +323,10 @@
 def fno_lto_unit: Flag<["-"], "fno-lto-unit">;
 def fthin_link_bitcode_EQ : Joined<["-"], "fthin-link-bitcode=">,
     HelpText<"Write minimized bitcode to <file> for the ThinLTO thin link only">;
+def fdebug_pass_manager : Flag<["-"], "fdebug-pass-manager">,
+    HelpText<"Prints debug information for the new pass manager">;
+def fno_debug_pass_manager : Flag<["-"], "fno-debug-pass-manager">,
+    HelpText<"Disables debug printing for the new pass manager">;
 
 //===----------------------------------------------------------------------===//
 // Dependency Output Options
Index: cfe/trunk/include/clang/Frontend/CodeGenOptions.def
===================================================================
--- cfe/trunk/include/clang/Frontend/CodeGenOptions.def
+++ cfe/trunk/include/clang/Frontend/CodeGenOptions.def
@@ -57,6 +57,8 @@
 CODEGENOPT(DisableO0ImplyOptNone , 1, 0) ///< Don't annonate function with optnone at O0
 CODEGENOPT(ExperimentalNewPassManager, 1, 0) ///< Enables the new, experimental
                                              ///< pass manager.
+CODEGENOPT(DebugPassManager, 1, 0) ///< Prints debug information for the new
+                                   ///< pass manager.
 CODEGENOPT(DisableRedZone    , 1, 0) ///< Set when -mno-red-zone is enabled.
 CODEGENOPT(DisableTailCalls  , 1, 0) ///< Do not emit tail calls.
 CODEGENOPT(EmitDeclMetadata  , 1, 0) ///< Emit special metadata indicating what
Index: cfe/trunk/lib/CodeGen/BackendUtil.cpp
===================================================================
--- cfe/trunk/lib/CodeGen/BackendUtil.cpp
+++ cfe/trunk/lib/CodeGen/BackendUtil.cpp
@@ -879,7 +879,7 @@
   PB.registerLoopAnalyses(LAM);
   PB.crossRegisterProxies(LAM, FAM, CGAM, MAM);
 
-  ModulePassManager MPM;
+  ModulePassManager MPM(CodeGenOpts.DebugPassManager);
 
   if (!CodeGenOpts.DisableLLVMPasses) {
     bool IsThinLTO = CodeGenOpts.EmitSummaryIndex;
@@ -897,12 +897,15 @@
       PassBuilder::OptimizationLevel Level = mapToLevel(CodeGenOpts);
 
       if (IsThinLTO) {
-        MPM = PB.buildThinLTOPreLinkDefaultPipeline(Level);
+        MPM = PB.buildThinLTOPreLinkDefaultPipeline(
+            Level, CodeGenOpts.DebugPassManager);
         MPM.addPass(NameAnonGlobalPass());
       } else if (IsLTO) {
-        MPM = PB.buildLTOPreLinkDefaultPipeline(Level);
+        MPM = PB.buildLTOPreLinkDefaultPipeline(Level,
+                                                CodeGenOpts.DebugPassManager);
       } else {
-        MPM = PB.buildPerModuleDefaultPipeline(Level);
+        MPM = PB.buildPerModuleDefaultPipeline(Level,
+                                               CodeGenOpts.DebugPassManager);
       }
     }
   }
Index: cfe/trunk/lib/Frontend/CompilerInvocation.cpp
===================================================================
--- cfe/trunk/lib/Frontend/CompilerInvocation.cpp
+++ cfe/trunk/lib/Frontend/CompilerInvocation.cpp
@@ -476,6 +476,10 @@
       OPT_fexperimental_new_pass_manager, OPT_fno_experimental_new_pass_manager,
       /* Default */ false);
 
+  Opts.DebugPassManager =
+      Args.hasFlag(OPT_fdebug_pass_manager, OPT_fno_debug_pass_manager,
+                   /* Default */ false);
+
   if (Arg *A = Args.getLastArg(OPT_fveclib)) {
     StringRef Name = A->getValue();
     if (Name == "Accelerate")
Index: cfe/trunk/test/CodeGen/lto-newpm-pipeline.c
===================================================================
--- cfe/trunk/test/CodeGen/lto-newpm-pipeline.c
+++ cfe/trunk/test/CodeGen/lto-newpm-pipeline.c
@@ -0,0 +1,53 @@
+// REQUIRES: x86-registered-target
+
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=full -O0 %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-FULL-O0
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=thin -O0 %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-THIN-O0
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=full -O1 %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-FULL-OPTIMIZED
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=thin -O1 %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-THIN-OPTIMIZED
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=full -O2 %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-FULL-OPTIMIZED
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=thin -O2 %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-THIN-OPTIMIZED
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=full -O3 %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-FULL-OPTIMIZED
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=thin -O3 %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-THIN-OPTIMIZED
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=full -Os %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-FULL-OPTIMIZED
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=thin -Os %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-THIN-OPTIMIZED
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=full -Oz %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-FULL-OPTIMIZED
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm-bc -o /dev/null -fexperimental-new-pass-manager -fdebug-pass-manager -flto=thin -Oz %s 2>&1 | FileCheck %s \
+// RUN:   -check-prefix=CHECK-THIN-OPTIMIZED
+
+// CHECK-FULL-O0: Starting llvm::Module pass manager run.
+// CHECK-FULL-O0: Running pass: AlwaysInlinerPass
+// CHECK-FULL-O0-NEXT: Running pass: BitcodeWriterPass
+// CHECK-FULL-O0: Finished llvm::Module pass manager run.
+
+// CHECK-THIN-O0: Starting llvm::Module pass manager run.
+// CHECK-THIN-O0: Running pass: AlwaysInlinerPass
+// CHECK-THIN-O0-NEXT: Running pass: NameAnonGlobalPass
+// CHECK-THIN-O0-NEXT: Running pass: ThinLTOBitcodeWriterPass
+// CHECK-THIN-O0: Finished llvm::Module pass manager run.
+
+// TODO: The LTO pre-link pipeline currently invokes
+//       buildPerModuleDefaultPipeline(), which contains LoopVectorizePass.
+//       This may change as the pipeline gets implemented.
+// CHECK-FULL-OPTIMIZED: Starting llvm::Function pass manager run.
+// CHECK-FULL-OPTIMIZED: Running pass: LoopVectorizePass
+// CHECK-FULL-OPTIMIZED: Running pass: BitcodeWriterPass
+
+// The ThinLTO pre-link pipeline shouldn't contain passes like
+// LoopVectorizePass.
+// CHECK-THIN-OPTIMIZED: Starting llvm::Function pass manager run.
+// CHECK-THIN-OPTIMIZED-NOT: Running pass: LoopVectorizePass
+// CHECK-THIN-OPTIMIZED: Running pass: NameAnonGlobalPass
+// CHECK-THIN-OPTIMIZED: Running pass: ThinLTOBitcodeWriterPass
+
+void Foo() {}