diff --git a/llvm/include/llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h b/llvm/include/llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h
--- a/llvm/include/llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h
+++ b/llvm/include/llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h
@@ -214,13 +214,22 @@
 }
 
 #ifndef NDEBUG
+template <typename BT> static inline std::string getName(const BT *BB) {
+  if (BB->hasName())
+    return BB->getName().str();
+  std::string Str;
+  raw_string_ostream OS(Str);
+  BB->printAsOperand(OS, false);
+  return Str;
+}
+
 /// Print the weight of edge \p E on stream \p OS.
 ///
 /// \param OS  Stream to emit the output to.
 /// \param E  Edge to print.
 template <typename BT>
 void SampleProfileLoaderBaseImpl<BT>::printEdgeWeight(raw_ostream &OS, Edge E) {
-  OS << "weight[" << E.first->getName() << "->" << E.second->getName()
+  OS << "weight[" << getName(E.first) << "->" << getName(E.second)
      << "]: " << EdgeWeights[E] << "\n";
 }
 
@@ -232,8 +241,8 @@
 void SampleProfileLoaderBaseImpl<BT>::printBlockEquivalence(
     raw_ostream &OS, const BasicBlockT *BB) {
   const BasicBlockT *Equiv = EquivalenceClass[BB];
-  OS << "equivalence[" << BB->getName()
-     << "]: " << ((Equiv) ? EquivalenceClass[BB]->getName() : "NONE") << "\n";
+  OS << "equivalence[" << getName(BB)
+     << "]: " << ((Equiv) ? getName(EquivalenceClass[BB]) : "NONE") << "\n";
 }
 
 /// Print the weight of block \p BB on stream \p OS.
@@ -245,7 +254,7 @@
     raw_ostream &OS, const BasicBlockT *BB) const {
   const auto &I = BlockWeights.find(BB);
   uint64_t W = (I == BlockWeights.end() ? 0 : I->second);
-  OS << "weight[" << BB->getName() << "]: " << W << "\n";
+  OS << "weight[" << getName(BB) << "]: " << W << "\n";
 }
 #endif
 
diff --git a/llvm/lib/Transforms/IPO/SampleProfile.cpp b/llvm/lib/Transforms/IPO/SampleProfile.cpp
--- a/llvm/lib/Transforms/IPO/SampleProfile.cpp
+++ b/llvm/lib/Transforms/IPO/SampleProfile.cpp
@@ -886,6 +886,8 @@
     auto *DI = &pgo::promoteIndirectCall(
         CI, R->getValue(), Candidate.CallsiteCount, Sum, false, ORE);
     if (DI) {
+      LLVM_DEBUG(dbgs() << "Promoted indirect call " << CI << "\n"
+                        << " to " << *DI << "\n");
       Sum -= Candidate.CallsiteCount;
       // Do not prorate the indirect callsite distribution since the original
       // distribution will be used to scale down non-promoted profile target
@@ -1173,15 +1175,24 @@
   if (Cost.isNever()) {
     ORE->emit(OptimizationRemarkAnalysis(CSINLINE_DEBUG, "InlineFail", DLoc, BB)
               << "incompatible inlining");
+    LLVM_DEBUG(dbgs() << "Failed to inline call " << CB
+                      << "\n because of incompatible inlining\n");
     return false;
   }
 
-  if (!Cost)
+  if (!Cost) {
+    LLVM_DEBUG(dbgs() << "Failed to inline call " << CB
+                      << "\n with CallsiteCount " << Candidate.CallsiteCount
+                      << " HotCountThreshold " << PSI->getHotCountThreshold()
+                      << " Cost " << Cost.getCost() << " CostThreshold "
+                      << Cost.getThreshold() << "\n");
     return false;
+  }
 
   InlineFunctionInfo IFI(nullptr, GetAC);
   IFI.UpdateProfile = false;
-  if (InlineFunction(CB, IFI).isSuccess()) {
+  InlineResult IR = InlineFunction(CB, IFI);
+  if (IR.isSuccess()) {
     // The call to InlineFunction erases I, so we can't pass it here.
     emitInlinedInto(*ORE, DLoc, BB, *CalledFunction, *BB->getParent(), Cost,
                     true, CSINLINE_DEBUG);
@@ -1213,7 +1224,18 @@
       NumDuplicatedInlinesite++;
     }
 
+    LLVM_DEBUG(dbgs() << "Inlined " << CalledFunction->getName() << "\n");
     return true;
+  } else {
+    ORE->emit([&]() {
+      return OptimizationRemarkMissed(CSINLINE_DEBUG, "NotInlined", DLoc, BB)
+             << ore::NV("Callee", CalledFunction)
+             << " will not be inlined into "
+             << ore::NV("Caller", BB->getParent()) << ": "
+             << ore::NV("Reason", IR.getFailureReason());
+    });
+    LLVM_DEBUG(dbgs() << "Failed to inline call " << CB << "\n because of "
+                      << IR.getFailureReason() << "\n");
   }
   return false;
 }
@@ -1243,6 +1265,7 @@
         CallsiteCount, uint64_t(CalleeSamples->getEntrySamples() * Factor));
 
   *NewCandidate = {CB, CalleeSamples, CallsiteCount, Factor};
+  LLVM_DEBUG(dbgs() << "Inline Candidate: " << *CB << "\n");
   return true;
 }
 
@@ -1300,7 +1323,7 @@
 
 bool SampleProfileLoader::inlineHotFunctionsWithPriority(
     Function &F, DenseSet<GlobalValue::GUID> &InlinedGUIDs) {
-  assert(ProfileIsCS && "Prioritiy based inliner only works with CSSPGO now");
+  assert(ProfileIsCS && "Priority based inliner only works with CSSPGO now");
 
   // ProfAccForSymsInList is used in callsiteIsHot. The assertion makes sure
   // Profile symbol list is ignored when profile-sample-accurate is on.
@@ -1407,6 +1430,7 @@
   }
 
   if (!CQueue.empty()) {
+    LLVM_DEBUG(dbgs() << "Inlining stopped, out of budget\n");
     if (SizeLimit == (unsigned)ProfileInlineLimitMax)
       ++NumCSInlinedHitMaxLimit;
     else if (SizeLimit == (unsigned)ProfileInlineLimitMin)