Index: lib/Transforms/Instrumentation/PGOInstrumentation.cpp
===================================================================
--- lib/Transforms/Instrumentation/PGOInstrumentation.cpp
+++ lib/Transforms/Instrumentation/PGOInstrumentation.cpp
@@ -884,12 +884,18 @@
       }
       if (Count->CountValid) {
         if (Count->UnknownCountOutEdge == 1) {
-          uint64_t Total = Count->CountValue - sumEdgeCount(Count->OutEdges);
+          uint64_t Total = 0;
+          uint64_t OutSum = sumEdgeCount(Count->OutEdges);
+          if (Count->CountValue > OutSum)
+            Total = Count->CountValue - OutSum;
           setEdgeCount(Count->OutEdges, Total);
           Changes = true;
         }
         if (Count->UnknownCountInEdge == 1) {
-          uint64_t Total = Count->CountValue - sumEdgeCount(Count->InEdges);
+          uint64_t Total = 0;
+          uint64_t InSum = sumEdgeCount(Count->InEdges);
+          if (Count->CountValue > InSum)
+            Total = Count->CountValue - InSum;
           setEdgeCount(Count->InEdges, Total);
           Changes = true;
         }
Index: test/Transforms/PGOProfile/Inputs/noreturncall.proftext
===================================================================
--- /dev/null
+++ test/Transforms/PGOProfile/Inputs/noreturncall.proftext
@@ -0,0 +1,11 @@
+# IR level Instrumentation Flag
+:ir
+foo
+# Func Hash:
+36496524737
+# Num Counters:
+3
+# Counter Values:
+20
+21
+0
Index: test/Transforms/PGOProfile/noreturncall.ll
===================================================================
--- /dev/null
+++ test/Transforms/PGOProfile/noreturncall.ll
@@ -0,0 +1,47 @@
+; RUN: llvm-profdata merge %S/Inputs/noreturncall.proftext -o %t.profdata
+; RUN: opt < %s -pgo-instr-use -pgo-test-profile-file=%t.profdata -S -debug-only=pgo-instrumentation 2>&1 | FileCheck %s --check-prefix=USE
+; RUN: opt < %s -passes=pgo-instr-use -pgo-test-profile-file=%t.profdata -S -debug-only=pgo-instrumentation 2>&1 | FileCheck %s --check-prefix=USE
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+declare i32 @bar0(i32)
+declare void @exit(i32)
+
+define i32 @bar2(i32 %i) {
+entry:
+  unreachable
+}
+
+define i32 @foo(i32 %i, i32 %j, i32 %k) {
+entry:
+  %cmp = icmp slt i32 %i, 999
+  br i1 %cmp, label %if.then, label %if.end
+
+if.then:
+  %call = call i32 @bar0(i32 %i)
+  br label %if.end
+
+if.end:
+  %ret.0 = phi i32 [ %call, %if.then ], [ 0, %entry ]
+  %cmp1 = icmp sgt i32 %j, 1000
+  %cmp3 = icmp sgt i32 %k, 99
+  %or.cond = and i1 %cmp1, %cmp3
+  br i1 %or.cond, label %if.then4, label %if.end7
+
+if.then4:
+  %call5 = call i32 @bar2(i32 undef)
+  br label %if.end7
+
+if.end7:
+  %mul = mul nsw i32 %ret.0, %ret.0
+  ret i32 %mul
+}
+; USE:  Edge 0: 1-->3  c  W=8000  Count=0
+; USE:  Edge 1: 3-->5  c  W=8000  Count=20
+; USE:  Edge 2: 0-->1     W=16  Count=21
+; USE:  Edge 3: 5-->0 *   W=16  Count=20
+; USE:  Edge 4: 1-->2     W=8  Count=21
+; USE:  Edge 5: 2-->3 *   W=8  Count=21
+; USE:  Edge 6: 3-->4     W=8  Count=0
+; USE:  Edge 7: 4-->5 *   W=8  Count=0