Index: llvm/trunk/docs/CommandGuide/llvm-profdata.rst
===================================================================
--- llvm/trunk/docs/CommandGuide/llvm-profdata.rst
+++ llvm/trunk/docs/CommandGuide/llvm-profdata.rst
@@ -192,6 +192,12 @@
  information is dumped in a more human readable form (also in text) with
  annotations.
 
+.. option:: -topn=n
+	     
+ Instruct the profile dumper to show the top ``n`` functions with the
+ hottest basic blocks in the summary section. By default, the topn functions
+ are not dumped.
+
 .. option:: -sample
 
  Specify that the input profile is a sample-based profile.
Index: llvm/trunk/test/tools/llvm-profdata/c-general.test
===================================================================
--- llvm/trunk/test/tools/llvm-profdata/c-general.test
+++ llvm/trunk/test/tools/llvm-profdata/c-general.test
@@ -10,6 +10,7 @@
 REGENERATE: $ LLVM_PROFILE_FILE=$TESTDIR/Inputs/c-general.profraw ./a.out
 
 RUN: llvm-profdata show %p/Inputs/c-general.profraw -o - | FileCheck %s
+RUN: llvm-profdata show %p/Inputs/c-general.profraw --topn=3 -o - | FileCheck %s --check-prefix=TOPN
 RUN: llvm-profdata show %p/Inputs/c-general.profraw -o - --function=switches | FileCheck %s -check-prefix=SWITCHES -check-prefix=CHECK
 
 SWITCHES-LABEL: Counters:
@@ -22,3 +23,6 @@
 CHECK-LABEL: Total functions: 12
 CHECK-NEXT: Maximum function count: 1
 CHECK-NEXT: Maximum internal block count: 100
+TOPN: boolean_operators, max count = 100
+TOPN-NEXT: simple_loops, max count = 100
+TOPN-NEXT:  conditionals, max count = 100
Index: llvm/trunk/tools/llvm-profdata/llvm-profdata.cpp
===================================================================
--- llvm/trunk/tools/llvm-profdata/llvm-profdata.cpp
+++ llvm/trunk/tools/llvm-profdata/llvm-profdata.cpp
@@ -512,8 +512,8 @@
 }
 
 static int showInstrProfile(const std::string &Filename, bool ShowCounts,
-                            bool ShowIndirectCallTargets, bool ShowMemOPSizes,
-                            bool ShowDetailedSummary,
+                            uint32_t TopN, bool ShowIndirectCallTargets,
+                            bool ShowMemOPSizes, bool ShowDetailedSummary,
                             std::vector<uint32_t> DetailedSummaryCutoffs,
                             bool ShowAllFunctions,
                             const std::string &ShowFunction, bool TextFormat,
@@ -532,6 +532,17 @@
   size_t ShownFunctions = 0;
   int NumVPKind = IPVK_Last - IPVK_First + 1;
   std::vector<ValueSitesStats> VPStats(NumVPKind);
+
+  auto MinCmp = [](const std::pair<std::string, uint64_t> &v1,
+                   const std::pair<std::string, uint64_t> &v2) {
+    return v1.second > v2.second;
+  };
+
+  std::priority_queue<std::pair<std::string, uint64_t>,
+                      std::vector<std::pair<std::string, uint64_t>>,
+                      decltype(MinCmp)>
+      HottestFuncs(MinCmp);
+
   for (const auto &Func : *Reader) {
     bool Show =
         ShowAllFunctions || (!ShowFunction.empty() &&
@@ -549,6 +560,20 @@
     assert(Func.Counts.size() > 0 && "function missing entry counter");
     Builder.addRecord(Func);
 
+    if (TopN) {
+      uint64_t FuncMax = 0;
+      for (size_t I = 0, E = Func.Counts.size(); I < E; ++I)
+        FuncMax = std::max(FuncMax, Func.Counts[I]);
+
+      if (HottestFuncs.size() == TopN) {
+        if (HottestFuncs.top().second < FuncMax) {
+          HottestFuncs.pop();
+          HottestFuncs.emplace(std::make_pair(std::string(Func.Name), FuncMax));
+        }
+      } else
+        HottestFuncs.emplace(std::make_pair(std::string(Func.Name), FuncMax));
+    }
+
     if (Show) {
 
       if (!ShownFunctions)
@@ -606,6 +631,18 @@
   OS << "Maximum function count: " << PS->getMaxFunctionCount() << "\n";
   OS << "Maximum internal block count: " << PS->getMaxInternalCount() << "\n";
 
+  if (TopN) {
+    std::vector<std::pair<std::string, uint64_t>> SortedHottestFuncs;
+    while (!HottestFuncs.empty()) {
+      SortedHottestFuncs.emplace_back(HottestFuncs.top());
+      HottestFuncs.pop();
+    }
+    OS << "Top " << TopN
+       << " functions with the largest internal block counts: \n";
+    for (auto &hotfunc : llvm::reverse(SortedHottestFuncs))
+      OS << "  " << hotfunc.first << ", max count = " << hotfunc.second << "\n";
+  }
+
   if (ShownFunctions && ShowIndirectCallTargets) {
     OS << "Statistics for indirect call sites profile:\n";
     showValueSitesStats(OS, IPVK_IndirectCallTarget,
@@ -689,6 +726,9 @@
       cl::desc("Profile kind:"), cl::init(instr),
       cl::values(clEnumVal(instr, "Instrumentation profile (default)"),
                  clEnumVal(sample, "Sample profile")));
+  cl::opt<uint32_t> TopNFunctions(
+      "topn", cl::init(0),
+      cl::desc("Show the list of functions with the largest internal counts"));
 
   cl::ParseCommandLineOptions(argc, argv, "LLVM profile data summary\n");
 
@@ -706,10 +746,10 @@
   std::vector<uint32_t> Cutoffs(DetailedSummaryCutoffs.begin(),
                                 DetailedSummaryCutoffs.end());
   if (ProfileKind == instr)
-    return showInstrProfile(Filename, ShowCounts, ShowIndirectCallTargets,
-                            ShowMemOPSizes, ShowDetailedSummary,
-                            DetailedSummaryCutoffs, ShowAllFunctions,
-                            ShowFunction, TextFormat, OS);
+    return showInstrProfile(Filename, ShowCounts, TopNFunctions,
+                            ShowIndirectCallTargets, ShowMemOPSizes,
+                            ShowDetailedSummary, DetailedSummaryCutoffs,
+                            ShowAllFunctions, ShowFunction, TextFormat, OS);
   else
     return showSampleProfile(Filename, ShowCounts, ShowAllFunctions,
                              ShowFunction, OS);