diff --git a/llvm/include/llvm/ProfileData/SampleProf.h b/llvm/include/llvm/ProfileData/SampleProf.h
--- a/llvm/include/llvm/ProfileData/SampleProf.h
+++ b/llvm/include/llvm/ProfileData/SampleProf.h
@@ -387,6 +387,13 @@
     return SortCallTargets(CallTargets);
   }
 
+  uint64_t getCallTargetSum() const {
+    uint64_t Sum = 0;
+    for (const auto &I : CallTargets)
+      Sum += I.second;
+    return Sum;
+  }
+
   /// Sort call targets in descending order of call frequency.
   static const SortedCallTargetSet SortCallTargets(const CallTargetMap &Targets) {
     SortedCallTargetSet SortedTargets;
@@ -779,6 +786,19 @@
     return BodySamples[LineLocation(Index, 0)].merge(S, Weight);
   }
 
+  // Accumulate all call target samples to update the body samples.
+  void updateCallsiteSamples() {
+    for (auto &I : BodySamples) {
+      uint64_t TargetSamples = I.second.getCallTargetSum();
+      // It's possible that the body sample count can be greater than the call
+      // target sum. E.g, if some call targets are external targets, they won't
+      // be considered valid call targets, but the body sample count which is
+      // from lbr ranges can actually include them.
+      if (TargetSamples > I.second.getSamples())
+        I.second.addSamples(TargetSamples - I.second.getSamples());
+    }
+  }
+
   // Accumulate all body samples to set total samples.
   void updateTotalSamples() {
     setTotalSamples(0);
diff --git a/llvm/test/tools/llvm-profgen/inline-noprobe2.test b/llvm/test/tools/llvm-profgen/inline-noprobe2.test
--- a/llvm/test/tools/llvm-profgen/inline-noprobe2.test
+++ b/llvm/test/tools/llvm-profgen/inline-noprobe2.test
@@ -59,7 +59,7 @@
 ;CHECK:  6.1: 17
 ;CHECK:  6.3: 17
 ;CHECK:  7: 0
-;CHECK:  8: 0 quick_sort:1
+;CHECK:  8: 1 quick_sort:1
 ;CHECK:  9: 0
 ;CHECK:  11: 0
 ;CHECK:  14: 0
@@ -97,7 +97,7 @@
 ;CHECK: quick_sort:903:25
 ;CHECK:  1: 24
 ;CHECK:  2: 12 partition_pivot_last:7 partition_pivot_first:5
-;CHECK:  3: 11 quick_sort:12
+;CHECK:  3: 12 quick_sort:12
 ;CHECK:  4: 12 quick_sort:12
 ;CHECK:  6: 24
 ;CHECK:  65507: 12
diff --git a/llvm/test/tools/llvm-profgen/noinline-noprobe.test b/llvm/test/tools/llvm-profgen/noinline-noprobe.test
--- a/llvm/test/tools/llvm-profgen/noinline-noprobe.test
+++ b/llvm/test/tools/llvm-profgen/noinline-noprobe.test
@@ -11,7 +11,7 @@
 ;CHECK:  0: 0
 ;CHECK:  1: 0
 ;CHECK:  2: 19
-;CHECK:  3: 19 bar:21
+;CHECK:  3: 21 bar:21
 ;CHECK:  4: 0
 ;CHECK:  5: 0
 ;CHECK: bar:926:21
diff --git a/llvm/test/tools/llvm-profgen/update-samples.test b/llvm/test/tools/llvm-profgen/update-samples.test
new file mode 100644
--- /dev/null
+++ b/llvm/test/tools/llvm-profgen/update-samples.test
@@ -0,0 +1,45 @@
+; RUN: llvm-profgen --format=text --perfscript=%S/Inputs/noprobe.perfscript --binary=%S/Inputs/noprobe.perfbin --output=%t1
+; RUN: FileCheck %s --input-file %t1 --check-prefix=CALLSITE
+; RUN: llvm-profgen --format=text --perfscript=%S/Inputs/noprobe.perfscript --binary=%S/Inputs/noprobe.perfbin --output=%t2 --update-total-samples=1
+; RUN: FileCheck %s --input-file %t2 --check-prefix=TOTAL
+
+
+;CALLSITE: foo:1241:0
+;CALLSITE:  0: 0
+;CALLSITE:  1: 0
+;CALLSITE:  2: 19
+;CALLSITE:  3: 21 bar:21
+;CALLSITE:  4: 0
+;CALLSITE:  5: 0
+
+;TOTAL: foo:40:0
+;TOTAL:  0: 0
+;TOTAL:  1: 0
+;TOTAL:  2: 19
+;TOTAL:  3: 21 bar:21
+;TOTAL:  4: 0
+;TOTAL:  5: 0
+
+
+; original code:
+; clang -O3 -g -fdebug-info-for-profiling test.c -fno-inline -o a.out
+#include <stdio.h>
+
+int bar(int x, int y) {
+  if (x % 3) {
+    return x - y;
+  }
+  return x + y;
+}
+
+void foo() {
+  int s, i = 0;
+  while (i++ < 4000 * 4000)
+    if (i % 91) s = bar(i, s); else s += 30;
+  printf("sum is %d\n", s);
+}
+
+int main() {
+  foo();
+  return 0;
+}
diff --git a/llvm/tools/llvm-profgen/ProfileGenerator.h b/llvm/tools/llvm-profgen/ProfileGenerator.h
--- a/llvm/tools/llvm-profgen/ProfileGenerator.h
+++ b/llvm/tools/llvm-profgen/ProfileGenerator.h
@@ -100,8 +100,13 @@
   void updateBodySamplesforFunctionProfile(FunctionSamples &FunctionProfile,
                                            const SampleContextFrame &LeafLoc,
                                            uint64_t Count);
+
+  void updateFunctionSamples();
+
   void updateTotalSamples();
 
+  void updateCallsiteSamples();
+
   StringRef getCalleeNameForOffset(uint64_t TargetOffset);
 
   void computeSummaryAndThreshold();
diff --git a/llvm/tools/llvm-profgen/ProfileGenerator.cpp b/llvm/tools/llvm-profgen/ProfileGenerator.cpp
--- a/llvm/tools/llvm-profgen/ProfileGenerator.cpp
+++ b/llvm/tools/llvm-profgen/ProfileGenerator.cpp
@@ -381,15 +381,26 @@
 }
 
 void ProfileGeneratorBase::updateTotalSamples() {
-  if (!UpdateTotalSamples)
-    return;
-
   for (auto &Item : ProfileMap) {
     FunctionSamples &FunctionProfile = Item.second;
     FunctionProfile.updateTotalSamples();
   }
 }
 
+void ProfileGeneratorBase::updateCallsiteSamples() {
+  for (auto &Item : ProfileMap) {
+    FunctionSamples &FunctionProfile = Item.second;
+    FunctionProfile.updateCallsiteSamples();
+  }
+}
+
+void ProfileGeneratorBase::updateFunctionSamples() {
+  updateCallsiteSamples();
+
+  if (UpdateTotalSamples)
+    updateTotalSamples();
+}
+
 void ProfileGeneratorBase::collectProfiledFunctions() {
   std::unordered_set<const BinaryFunction *> ProfiledFunctions;
   if (SampleCounters) {
@@ -491,7 +502,7 @@
   // Fill in boundary sample counts as well as call site samples for calls
   populateBoundarySamplesForAllFunctions(SC.BranchCounter);
 
-  updateTotalSamples();
+  updateFunctionSamples();
 }
 
 void ProfileGenerator::generateProbeBasedProfile() {
@@ -505,7 +516,7 @@
   // Fill in boundary sample counts as well as call site samples for calls
   populateBoundarySamplesWithProbesForAllFunctions(SC.BranchCounter);
 
-  updateTotalSamples();
+  updateFunctionSamples();
 }
 
 void ProfileGenerator::populateBodySamplesWithProbesForAllFunctions(
@@ -785,7 +796,7 @@
   // body sample.
   populateInferredFunctionSamples();
 
-  updateTotalSamples();
+  updateFunctionSamples();
 }
 
 void CSProfileGenerator::populateBodySamplesForFunction(