Index: llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
===================================================================
--- llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
+++ llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
@@ -1422,7 +1422,8 @@
         MaxCount = EdgeCount;
       EdgeCounts[SuccNum] = EdgeCount;
     }
-    setProfMetadata(M, TI, EdgeCounts, MaxCount);
+    if (MaxCount)
+      setProfMetadata(M, TI, EdgeCounts, MaxCount);
   }
 }
 
Index: llvm/lib/Transforms/Instrumentation/PGOMemOPSizeOpt.cpp
===================================================================
--- llvm/lib/Transforms/Instrumentation/PGOMemOPSizeOpt.cpp
+++ llvm/lib/Transforms/Instrumentation/PGOMemOPSizeOpt.cpp
@@ -440,7 +440,8 @@
   DTU.applyUpdates(Updates);
   Updates.clear();
 
-  setProfMetadata(Func.getParent(), SI, CaseCounts, MaxCount);
+  if (MaxCount)
+    setProfMetadata(Func.getParent(), SI, CaseCounts, MaxCount);
 
   LLVM_DEBUG(dbgs() << *BB << "\n");
   LLVM_DEBUG(dbgs() << *DefaultBB << "\n");
Index: llvm/test/Transforms/PGOProfile/Inputs/maxcountzero.proftext
===================================================================
--- /dev/null
+++ llvm/test/Transforms/PGOProfile/Inputs/maxcountzero.proftext
@@ -0,0 +1,16 @@
+# IR level Instrumentation Flag
+:ir
+foo
+# Func Hash:
+376260595403191007
+# Num Counters:
+8
+# Counter Values:
+0
+0
+10
+0
+0
+0
+0
+0
Index: llvm/test/Transforms/PGOProfile/maxcountzero.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/PGOProfile/maxcountzero.ll
@@ -0,0 +1,80 @@
+; Make sure a degenerate profile does not cause an assertion.
+; The profile consists of a non-zero count in a basic block and 0 counts
+; in all succcessor blocks.
+
+; RUN: llvm-profdata merge %S/Inputs/maxcountzero.proftext -o %t.profdata
+; RUN: opt < %s -passes=pgo-instr-use -pgo-instrument-entry=false -pgo-test-profile-file=%t.profdata -S | FileCheck %s
+
+%struct.II = type { ptr }
+@RR = hidden global ptr null, align 8
+@kk = hidden global %struct.II zeroinitializer, align 8
+
+define hidden void @foo(ptr noundef %ww) {
+entry:
+  %tmp = alloca i32, align 4
+  %ee = alloca i32, align 4
+  %0 = load i32, ptr %ww, align 4
+  %cmp = icmp sgt i32 %0, -1
+  br i1 %cmp, label %if.end, label %if.then
+
+if.then:
+  br label %if.end
+
+if.end:
+  %stmxcsr = load i32, ptr %tmp, align 4
+  %and = and i32 %stmxcsr, 32768
+  %cmp2.not.not = icmp eq i32 %and, 0
+  br i1 %cmp2.not.not, label %if.then3, label %if.end4
+
+if.then3:
+  br label %if.end4
+
+if.end4:
+  %call = call noundef zeroext i1 @_Z2NNv()
+  br i1 %call, label %if.end12, label %if.then5
+
+if.then5:
+  %call6 = call noundef zeroext i1 @_Z2NNv()
+  br i1 %call6, label %if.then7, label %if.end11
+
+if.then7:
+  %1 = load i32, ptr %ee, align 4
+  %cmp8 = icmp eq i32 %1, 1
+  br i1 %cmp8, label %if.then9, label %if.else
+
+if.then9:
+  br label %if.end11
+
+if.else:
+  br label %if.end11
+
+if.end11:
+  br label %if.end12
+
+if.end12:
+  br label %for.cond.i
+
+for.cond.i:
+  %2 = load ptr, ptr @RR, align 8
+  %tobool.not.i = icmp eq ptr %2, null
+  br i1 %tobool.not.i, label %if.end.i, label %if.then.i
+
+if.then.i:
+  %3 = load ptr, ptr @kk, align 8
+  call void %3(ptr noundef null)
+  br label %if.end.i
+
+if.end.i:
+  br label %for.cond.i
+}
+
+declare noundef zeroext i1 @_Z2NNv() local_unnamed_addr
+
+!llvm.module.flags = !{!0, !1, !2, !3}
+
+!0 = !{i32 1, !"wchar_size", i32 2}
+!1 = !{i32 7, !"PIC Level", i32 2}
+!2 = !{i32 7, !"uwtable", i32 2}
+!3 = !{i32 7, !"frame-pointer", i32 1}
+
+; CHECK: define