Index: lib/IR/Module.cpp
===================================================================
--- lib/IR/Module.cpp
+++ lib/IR/Module.cpp
@@ -512,7 +512,7 @@
 }
 
 void Module::setProfileSummary(Metadata *M) {
-  addModuleFlag(ModFlagBehavior::Error, "ProfileSummary", M);
+  addModuleFlag(ModFlagBehavior::Warning, "ProfileSummary", M);
 }
 
 Metadata *Module::getProfileSummary() {
Index: test/Transforms/PGOProfile/PR28219.ll
===================================================================
--- test/Transforms/PGOProfile/PR28219.ll
+++ test/Transforms/PGOProfile/PR28219.ll
@@ -6,7 +6,7 @@
 entry:
   ret i32 1
 }
-; CHECK-DAG: {{![0-9]+}} = !{i32 1, !"ProfileSummary", {{![0-9]+}}}
+; CHECK-DAG: {{![0-9]+}} = !{i32 2, !"ProfileSummary", {{![0-9]+}}}
 ; CHECK-DAG: {{![0-9]+}} = !{!"NumFunctions", i64 2}
 ; CHECK-DAG: {{![0-9]+}} = !{!"MaxFunctionCount", i64 3}
 
Index: test/Transforms/PGOProfile/branch1.ll
===================================================================
--- test/Transforms/PGOProfile/branch1.ll
+++ test/Transforms/PGOProfile/branch1.ll
@@ -44,6 +44,6 @@
   %retv = phi i32 [ %add, %if.then ], [ %i, %entry ]
   ret i32 %retv
 }
-; USE-DAG: {{![0-9]+}} = !{i32 1, !"ProfileSummary", {{![0-9]+}}}
+; USE-DAG: {{![0-9]+}} = !{i32 2, !"ProfileSummary", {{![0-9]+}}}
 ; USE-DAG: {{![0-9]+}} = !{!"DetailedSummary", {{![0-9]+}}}
 ; USE-DAG: ![[FUNC_ENTRY_COUNT]] = !{!"function_entry_count", i64 3}
Index: test/Transforms/SampleProfile/summary.ll
===================================================================
--- test/Transforms/SampleProfile/summary.ll
+++ test/Transforms/SampleProfile/summary.ll
@@ -6,7 +6,7 @@
   ret i32 1, !dbg !2
 }
 
-; CHECK-DAG: {{![0-9]+}} = !{i32 1, !"ProfileSummary", {{![0-9]+}}}
+; CHECK-DAG: {{![0-9]+}} = !{i32 2, !"ProfileSummary", {{![0-9]+}}}
 ; CHECK-DAG: {{![0-9]+}} = !{!"NumFunctions", i64 2}
 ; CHECK-DAG: {{![0-9]+}} = !{!"MaxFunctionCount", i64 3}