Index: lib/profile/InstrProfilingFile.c
===================================================================
--- lib/profile/InstrProfilingFile.c
+++ lib/profile/InstrProfilingFile.c
@@ -225,6 +225,11 @@
     fclose(ProfileFile);
     return NULL;
   }
+  // Truncate the file in case merging of value profile did not happend.
+  // (which can leave garbage at the end of profile file).
+  if (!VPMergeHook)
+    truncate(ProfileFileName, 0);
+
   return ProfileFile;
 }
 
@@ -234,6 +239,7 @@
   FILE *OutputFile;
 
   int MergeDone = 0;
+  VPMergeHook = &lprofMergeValueProfData;
   if (!doMerging())
     OutputFile = fopen(OutputName, "ab");
   else
Index: lib/profile/InstrProfilingMerge.c
===================================================================
--- lib/profile/InstrProfilingMerge.c
+++ lib/profile/InstrProfilingMerge.c
@@ -17,8 +17,9 @@
 #define INSTR_PROF_VALUE_PROF_DATA
 #include "InstrProfData.inc"
 
-COMPILER_RT_WEAK void (*VPMergeHook)(ValueProfData *,
-                                     __llvm_profile_data *) = NULL;
+COMPILER_RT_VISIBILITY
+void (*VPMergeHook)(ValueProfData *, __llvm_profile_data *);
+
 COMPILER_RT_VISIBILITY
 uint64_t lprofGetLoadModuleSignature() {
   /* A very fast way to compute a module signature.  */
Index: lib/profile/InstrProfilingMergeFile.c
===================================================================
--- lib/profile/InstrProfilingMergeFile.c
+++ lib/profile/InstrProfilingMergeFile.c
@@ -17,14 +17,11 @@
 #define INSTR_PROF_VALUE_PROF_DATA
 #include "InstrProfData.inc"
 
-void (*VPMergeHook)(ValueProfData *,
-                    __llvm_profile_data *) = &lprofMergeValueProfData;
-
 /* Merge value profile data pointed to by SrcValueProfData into
  * in-memory profile counters pointed by to DstData.  */
 void lprofMergeValueProfData(ValueProfData *SrcValueProfData,
                              __llvm_profile_data *DstData) {
-  unsigned I, S, V, C;
+  unsigned I, S, V, C, Index = 0;
   InstrProfValueData *VData;
   ValueProfRecord *VR = getFirstValueProfRecord(SrcValueProfData);
   for (I = 0; I < SrcValueProfData->NumValueKinds; I++) {
@@ -33,8 +30,9 @@
       uint8_t NV = VR->SiteCountArray[S];
       for (V = 0; V < NV; V++) {
         for (C = 0; C < VData[V].Count; C++)
-          __llvm_profile_instrument_target(VData[V].Value, DstData, S);
+          __llvm_profile_instrument_target(VData[S + V].Value, DstData, Index);
       }
+      ++Index;
     }
     VR = getValueProfRecordNext(VR);
   }
Index: test/profile/instrprof-value-merge.c
===================================================================
--- /dev/null
+++ test/profile/instrprof-value-merge.c
@@ -0,0 +1,48 @@
+// RUN: %clang_pgogen -o %t -O3 %s
+// RUN: rm -rf %t.profdir
+// RUN: env LLVM_PROFILE_FILE=%t.profdir/default_%m.profraw %run %t
+// RUN: env LLVM_PROFILE_FILE=%t.profdir/default_%m.profraw %run %t
+// RUN: env LLVM_PROFILE_FILE=%t.profdir/default_%m.profraw %run %t
+// RUN: env LLVM_PROFILE_FILE=%t.profdir/default_%m.profraw %run %t 1
+// RUN: env LLVM_PROFILE_FILE=%t.profdir/default_%m.profraw %run %t 1
+// RUN: llvm-profdata show -counts -function=main -ic-targets -memop-sizes %t.profdir/default_*.profraw | FileCheck %s
+
+#include <string.h>
+
+void (*f)();
+
+char dst[200];
+char src[200];
+volatile int n;
+
+__attribute__((noinline)) void foo() {}
+
+__attribute__((noinline)) void bar() {
+  f = foo;
+  n = 4;
+}
+int main(int argc, char *argv[]) {
+  bar();
+  if (argc == 1)
+    f();
+  else {
+    memcpy((void *)dst, (void *)src, n);
+    memcpy((void *)(dst + 2), (void *)src, n + 1);
+    memcpy((void *)(dst + 9), (void *)src, n + 2);
+  }
+}
+
+// CHECK:  main:
+// CHECK:    Hash: 0x00010006e852da94
+// CHECK:    Counters: 2
+// CHECK:    Indirect Call Site Count: 1
+// CHECK:    Number of Memory Intrinsics Calls: 3
+// CHECK:    Block counts: [3, 2]
+// CHECK:    Indirect Target Results:
+// CHECK:       [ 0, foo, 3 ]
+// CHECK:    Memory Intrinsic Size Results:
+// CHECK:       [ 0, 4, 2 ]
+// CHECK:       [ 1, 5, 2 ]
+// CHECK:       [ 2, 6, 2 ]
+// CHECK: Instrumentation level: IR
+