Index: llvm/trunk/lib/Transforms/Instrumentation/IndirectCallPromotion.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Instrumentation/IndirectCallPromotion.cpp
+++ llvm/trunk/lib/Transforms/Instrumentation/IndirectCallPromotion.cpp
@@ -872,6 +872,10 @@
 
   if (ActualCount < MemOPCountThreshold)
     return false;
+  // Skip if the total value profiled count is 0, in which case we can't
+  // scale up the counts properly (and there is no profitable transformation).
+  if (TotalCount == 0)
+    return false;
 
   TotalCount = ActualCount;
   if (MemOPScaleCount)
Index: llvm/trunk/test/Transforms/PGOProfile/memop_size_opt_zero.ll
===================================================================
--- llvm/trunk/test/Transforms/PGOProfile/memop_size_opt_zero.ll
+++ llvm/trunk/test/Transforms/PGOProfile/memop_size_opt_zero.ll
@@ -0,0 +1,19 @@
+; Test to ensure the pgo memop optimization pass doesn't try to scale
+; up a value profile with a 0 count, which would lead to divide by 0.
+; RUN: opt < %s -passes=pgo-memop-opt -pgo-memop-count-threshold=1 -S | FileCheck %s --check-prefix=MEMOP_OPT
+; RUN: opt < %s -pgo-memop-opt -pgo-memop-count-threshold=1 -S | FileCheck %s --check-prefix=MEMOP_OPT
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @foo(i8* %dst, i8* %src, i64 %conv) !prof !0 {
+  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %src, i64 %conv, i32 1, i1 false), !prof !1
+  ret void
+}
+
+; MEMOP_OPT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %src, i64 %conv, i32 1, i1 false), !prof !1
+
+!0 = !{!"function_entry_count", i64 1}
+!1 = !{!"VP", i32 1, i64 0, i64 1, i64 0, i64 2, i64 0, i64 3, i64 0, i64 9, i64 0, i64 4, i64 0, i64 5, i64 0, i64 6, i64 0, i64 7, i64 0, i64 8, i64 0}
+
+declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture writeonly, i8* nocapture readonly, i64, i32, i1)