Index: include/llvm/Analysis/ProfileSummaryInfo.h
===================================================================
--- include/llvm/Analysis/ProfileSummaryInfo.h
+++ include/llvm/Analysis/ProfileSummaryInfo.h
@@ -49,6 +49,10 @@
   void computeThresholds();
   // Count thresholds to answer isHotCount and isColdCount queries.
   Optional<uint64_t> HotCountThreshold, ColdCountThreshold;
+  /// Returns the profile count for \p CallInst.
+  static Optional<uint64_t> getProfileCount(const Instruction *CallInst,
+                                            BlockFrequencyInfo *BFI,
+                                            bool IsSamplePGO);
 
 public:
   ProfileSummaryInfo(Module &M) : M(M) {}
Index: include/llvm/IR/Module.h
===================================================================
--- include/llvm/IR/Module.h
+++ include/llvm/IR/Module.h
@@ -804,7 +804,7 @@
   void setProfileSummary(Metadata *M);
 
   /// \brief Returns profile summary metadata
-  Metadata *getProfileSummary();
+  Metadata *getProfileSummary() const;
   /// @}
 
   /// Take ownership of the given memory buffer.
Index: include/llvm/IR/ProfileSummary.h
===================================================================
--- include/llvm/IR/ProfileSummary.h
+++ include/llvm/IR/ProfileSummary.h
@@ -18,6 +18,7 @@
 #include <utility>
 #include <vector>
 
+#include "llvm/ADT/Optional.h"
 #include "llvm/Support/Casting.h"
 
 namespace llvm {
@@ -70,6 +71,8 @@
   Kind getKind() const { return PSK; }
   /// \brief Return summary information as metadata.
   Metadata *getMD(LLVMContext &Context);
+  /// Return the profile kind from metadata.
+  static Optional<ProfileSummary::Kind> getKindFromMD(Metadata *MD);
   /// \brief Construct profile summary from metdata.
   static ProfileSummary *getFromMD(Metadata *MD);
   SummaryEntryVector &getDetailedSummary() { return DetailedSummary; }
Index: lib/Analysis/ProfileSummaryInfo.cpp
===================================================================
--- lib/Analysis/ProfileSummaryInfo.cpp
+++ lib/Analysis/ProfileSummaryInfo.cpp
@@ -68,23 +68,44 @@
   return true;
 }
 
-Optional<uint64_t>
-ProfileSummaryInfo::getProfileCount(const Instruction *Inst,
-                                    BlockFrequencyInfo *BFI) {
+static Optional<ProfileSummary::Kind> getKind(const Module *M) {
+  auto *SummaryMD = M->getProfileSummary();
+  if (!SummaryMD)
+    return None;
+  return ProfileSummary::getKindFromMD(SummaryMD);
+}
+
+Optional<uint64_t> ProfileSummaryInfo::getProfileCount(const Instruction *Inst,
+                                                       BlockFrequencyInfo *BFI,
+                                                       bool IsSamplePGO) {
   if (!Inst)
     return None;
   assert((isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) &&
          "We can only get profile count for call/invoke instruction.");
-  // Check if there is a profile metadata on the instruction. If it is present,
-  // determine hotness solely based on that.
-  uint64_t TotalCount;
-  if (Inst->extractProfTotalWeight(TotalCount))
-    return TotalCount;
+  if (IsSamplePGO) {
+    // In sample PGO mode, check if there is a profile metadata on the
+    // instruction. If it is present, determine hotness solely based on that,
+    // since the sampled entry count may not be accurate.
+    uint64_t TotalCount;
+    if (Inst->extractProfTotalWeight(TotalCount))
+      return TotalCount;
+  }
   if (BFI)
     return BFI->getBlockProfileCount(Inst->getParent());
   return None;
 }
 
+Optional<uint64_t>
+ProfileSummaryInfo::getProfileCount(const Instruction *Inst,
+                                    BlockFrequencyInfo *BFI) {
+  if (!Inst)
+    return None;
+  bool IsSamplePGO = false;
+  if (auto Kind = getKind(Inst->getModule()))
+    IsSamplePGO = Kind.getValue() == ProfileSummary::PSK_Sample;
+  return getProfileCount(Inst, BFI, IsSamplePGO);
+}
+
 /// Returns true if the function's entry is hot. If it returns false, it
 /// either means it is not hot or it is unknown whether it is hot or not (for
 /// example, no profile data is available).
@@ -108,11 +129,13 @@
     if (isHotCount(FunctionCount.getValue()))
       return true;
 
+  assert(Summary.get());
   uint64_t TotalCallCount = 0;
   for (const auto &BB : *F)
     for (const auto &I : BB)
       if (isa<CallInst>(I) || isa<InvokeInst>(I))
-        if (auto CallCount = getProfileCount(&I, nullptr))
+        if (auto CallCount = getProfileCount(
+                &I, nullptr, Summary->getKind() == ProfileSummary::PSK_Sample))
           TotalCallCount += CallCount.getValue();
   return isHotCount(TotalCallCount);
 }
@@ -126,12 +149,14 @@
   if (auto FunctionCount = F->getEntryCount())
     if (!isColdCount(FunctionCount.getValue()))
       return false;
-  
+
+  assert(Summary.get());
   uint64_t TotalCallCount = 0;
   for (const auto &BB : *F)
     for (const auto &I : BB) 
       if (isa<CallInst>(I) || isa<InvokeInst>(I))
-        if (auto CallCount = getProfileCount(&I, nullptr))
+        if (auto CallCount = getProfileCount(
+                &I, nullptr, Summary->getKind() == ProfileSummary::PSK_Sample))
           TotalCallCount += CallCount.getValue();
   return isColdCount(TotalCallCount);
 }
@@ -189,13 +214,19 @@
 
 bool ProfileSummaryInfo::isHotCallSite(const CallSite &CS,
                                        BlockFrequencyInfo *BFI) {
-  auto C = getProfileCount(CS.getInstruction(), BFI);
+  if (!computeSummary())
+    return false;
+  auto C = getProfileCount(CS.getInstruction(), BFI,
+                           Summary->getKind() == ProfileSummary::PSK_Sample);
   return C && isHotCount(*C);
 }
 
 bool ProfileSummaryInfo::isColdCallSite(const CallSite &CS,
                                         BlockFrequencyInfo *BFI) {
-  auto C = getProfileCount(CS.getInstruction(), BFI);
+  if (!computeSummary())
+    return false;
+  auto C = getProfileCount(CS.getInstruction(), BFI,
+                           Summary->getKind() == ProfileSummary::PSK_Sample);
   return C && isColdCount(*C);
 }
 
Index: lib/IR/Module.cpp
===================================================================
--- lib/IR/Module.cpp
+++ lib/IR/Module.cpp
@@ -483,7 +483,7 @@
   addModuleFlag(ModFlagBehavior::Error, "ProfileSummary", M);
 }
 
-Metadata *Module::getProfileSummary() {
+Metadata *Module::getProfileSummary() const {
   return getModuleFlag("ProfileSummary");
 }
 
Index: lib/IR/ProfileSummary.cpp
===================================================================
--- lib/IR/ProfileSummary.cpp
+++ lib/IR/ProfileSummary.cpp
@@ -143,6 +143,26 @@
   return true;
 }
 
+Optional<ProfileSummary::Kind> ProfileSummary::getKindFromMD(Metadata *MD) {
+  if (!MD)
+    return None;
+  if (!isa<MDTuple>(MD))
+    return None;
+  MDTuple *Tuple = cast<MDTuple>(MD);
+  if (Tuple->getNumOperands() != 8)
+    return None;
+
+  auto &FormatMD = Tuple->getOperand(0);
+  if (isKeyValuePair(dyn_cast_or_null<MDTuple>(FormatMD), "ProfileFormat",
+                     "SampleProfile"))
+    return PSK_Sample;
+  else if (isKeyValuePair(dyn_cast_or_null<MDTuple>(FormatMD), "ProfileFormat",
+                          "InstrProf"))
+    return PSK_Instr;
+
+  return None;
+}
+
 ProfileSummary *ProfileSummary::getFromMD(Metadata *MD) {
   if (!MD)
     return nullptr;
Index: test/Bitcode/thinlto-function-summary-callgraph-profile-summary.ll
===================================================================
--- test/Bitcode/thinlto-function-summary-callgraph-profile-summary.ll
+++ test/Bitcode/thinlto-function-summary-callgraph-profile-summary.ll
@@ -29,7 +29,7 @@
 ; CHECK-NEXT:    <VERSION
 ; CHECK-NEXT:    <VALUE_GUID op0=25 op1=123/>
 ; op4=hot1 op6=cold op8=hot2 op10=hot4 op12=none1 op14=hot3 op16=none2 op18=none3 op20=123
-; CHECK-NEXT:    <PERMODULE_PROFILE {{.*}} op4=1 op5=3 op6=5 op7=1 op8=2 op9=3 op10=4 op11=3 op12=6 op13=2 op14=3 op15=3 op16=7 op17=2 op18=8 op19=2 op20=25 op21=3/>
+; CHECK-NEXT:    <PERMODULE_PROFILE {{.*}} op4=1 op5=3 op6=5 op7=1 op8=2 op9=3 op10=4 op11=1 op12=6 op13=2 op14=3 op15=3 op16=7 op17=2 op18=8 op19=2 op20=25 op21=3/>
 ; CHECK-NEXT:  </GLOBALVAL_SUMMARY_BLOCK>
 
 ; CHECK: <STRTAB_BLOCK
Index: test/Bitcode/thinlto-function-summary-callgraph-sample-profile-summary.ll
===================================================================
--- test/Bitcode/thinlto-function-summary-callgraph-sample-profile-summary.ll
+++ test/Bitcode/thinlto-function-summary-callgraph-sample-profile-summary.ll
@@ -106,7 +106,7 @@
 
 !1 = !{i32 1, !"ProfileSummary", !2}
 !2 = !{!3, !4, !5, !6, !7, !8, !9, !10}
-!3 = !{!"ProfileFormat", !"InstrProf"}
+!3 = !{!"ProfileFormat", !"SampleProfile"}
 !4 = !{!"TotalCount", i64 10000}
 !5 = !{!"MaxCount", i64 10}
 !6 = !{!"MaxInternalCount", i64 1}
Index: test/Transforms/CodeGenPrepare/section-samplepgo.ll
===================================================================
--- test/Transforms/CodeGenPrepare/section-samplepgo.ll
+++ test/Transforms/CodeGenPrepare/section-samplepgo.ll
@@ -39,7 +39,7 @@
 !llvm.module.flags = !{!1}
 !1 = !{i32 1, !"ProfileSummary", !2}
 !2 = !{!3, !4, !5, !6, !7, !8, !9, !10}
-!3 = !{!"ProfileFormat", !"InstrProf"}
+!3 = !{!"ProfileFormat", !"SampleProfile"}
 !4 = !{!"TotalCount", i64 10000}
 !5 = !{!"MaxCount", i64 1000}
 !6 = !{!"MaxInternalCount", i64 1}
Index: test/Transforms/CodeGenPrepare/section.ll
===================================================================
--- test/Transforms/CodeGenPrepare/section.ll
+++ test/Transforms/CodeGenPrepare/section.ll
@@ -10,26 +10,26 @@
   ret void
 }
 
-; CHECK: hot_call_func{{.*}}!section_prefix ![[HOT_ID]]
-; The sum of 2 callsites are hot
-define void @hot_call_func() !prof !16 {
+; For instrumentation based PGO, we should only look at entry counts,
+; not call site VP metadata (which can exist on value profiled memcpy,
+; or possibly left behind after static analysis based devirtualization).
+; CHECK: cold_func1{{.*}}!section_prefix ![[COLD_ID:[0-9]+]]
+define void @cold_func1() !prof !16 {
   call void @hot_func(), !prof !17
   call void @hot_func(), !prof !17
   ret void
 }
 
-; CHECK-NOT: normal_func{{.*}}!section_prefix
-; The sum of all callsites are neither hot or cold
-define void @normal_func() !prof !16 {
+; CHECK: cold_func2{{.*}}!section_prefix
+define void @cold_func2() !prof !16 {
   call void @hot_func(), !prof !17
   call void @hot_func(), !prof !18
   call void @hot_func(), !prof !18
   ret void
 }
 
-; CHECK: cold_func{{.*}}!section_prefix ![[COLD_ID:[0-9]+]]
-; The entry and the callsite are both cold
-define void @cold_func() !prof !16 {
+; CHECK: cold_func3{{.*}}!section_prefix ![[COLD_ID]]
+define void @cold_func3() !prof !16 {
   call void @hot_func(), !prof !18
   ret void
 }
Index: test/Transforms/Inline/prof-update.ll
===================================================================
--- test/Transforms/Inline/prof-update.ll
+++ test/Transforms/Inline/prof-update.ll
@@ -5,33 +5,46 @@
 declare void @ext1();
 
 ; CHECK: define void @callee(i32 %n) !prof ![[ENTRY_COUNT:[0-9]*]]
-define void  @callee(i32 %n) !prof !1 {
+define void  @callee(i32 %n) !prof !15 {
   %cond = icmp sle i32 %n, 10
   br i1 %cond, label %cond_true, label %cond_false
 cond_true:
 ; ext1 is optimized away, thus not updated.
 ; CHECK: call void @ext1(), !prof ![[COUNT_CALLEE1:[0-9]*]]
-  call void @ext1(), !prof !2
+  call void @ext1(), !prof !16
   ret void
 cond_false:
 ; ext is cloned and updated.
 ; CHECK: call void @ext(), !prof ![[COUNT_CALLEE:[0-9]*]]
-  call void @ext(), !prof !2
+  call void @ext(), !prof !16
   ret void
 }
 
 ; CHECK: define void @caller()
 define void @caller() {
 ; CHECK: call void @ext(), !prof ![[COUNT_CALLER:[0-9]*]]
-  call void @callee(i32 15), !prof !3
+  call void @callee(i32 15), !prof !17
   ret void
 }
 
-!llvm.module.flags = !{!0}
-!0 = !{i32 1, !"MaxFunctionCount", i32 2000}
-!1 = !{!"function_entry_count", i64 1000}
-!2 = !{!"branch_weights", i64 2000}
-!3 = !{!"branch_weights", i64 400}
+!llvm.module.flags = !{!1}
+!1 = !{i32 1, !"ProfileSummary", !2}
+!2 = !{!3, !4, !5, !6, !7, !8, !9, !10}
+!3 = !{!"ProfileFormat", !"SampleProfile"}
+!4 = !{!"TotalCount", i64 10000}
+!5 = !{!"MaxCount", i64 10}
+!6 = !{!"MaxInternalCount", i64 1}
+!7 = !{!"MaxFunctionCount", i64 2000}
+!8 = !{!"NumCounts", i64 2}
+!9 = !{!"NumFunctions", i64 2}
+!10 = !{!"DetailedSummary", !11}
+!11 = !{!12, !13, !14}
+!12 = !{i32 10000, i64 100, i32 1}
+!13 = !{i32 999000, i64 100, i32 1}
+!14 = !{i32 999999, i64 1, i32 2}
+!15 = !{!"function_entry_count", i64 1000}
+!16 = !{!"branch_weights", i64 2000}
+!17 = !{!"branch_weights", i64 400}
 attributes #0 = { alwaysinline }
 ; CHECK: ![[ENTRY_COUNT]] = !{!"function_entry_count", i64 600}
 ; CHECK: ![[COUNT_CALLEE1]] = !{!"branch_weights", i64 2000}
Index: unittests/Analysis/ProfileSummaryInfoTest.cpp
===================================================================
--- unittests/Analysis/ProfileSummaryInfoTest.cpp
+++ unittests/Analysis/ProfileSummaryInfoTest.cpp
@@ -162,6 +162,12 @@
 
   EXPECT_TRUE(PSI.isHotCallSite(CS1, &BFI));
   EXPECT_FALSE(PSI.isHotCallSite(CS2, &BFI));
+
+  // Test that adding an MD_prof metadata with a hot count on CS2 does not
+  // change its hotness as it has no effect in instrumented profiling.
+  MDBuilder MDB(M->getContext());
+  CI2->setMetadata(llvm::LLVMContext::MD_prof, MDB.createBranchWeights({400}));
+  EXPECT_FALSE(PSI.isHotCallSite(CS2, &BFI));
 }
 
 TEST_F(ProfileSummaryInfoTest, SampleProf) {