Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -2498,7 +2498,8 @@
 def err_attribute_bad_neon_vector_size : Error<
   "Neon vector size must be 64 or 128 bits">;
 def err_attribute_requires_positive_integer : Error<
-  "%0 attribute requires a positive integral compile time constant expression">;
+  "%0 attribute requires a %select{positive|non-negative}1 "
+  "integral compile time constant expression">;
 def err_attribute_requires_opencl_version : Error<
   "%0 attribute requires OpenCL version %1%select{| or above}2">;
 def warn_unsupported_target_attribute
@@ -2531,8 +2532,6 @@
   "constant|a string|an identifier}1">;
 def err_attribute_argument_outof_range : Error<
   "%0 attribute requires integer constant between %1 and %2 inclusive">;
-def err_attribute_argument_negative : Error<
-  "negative argument is not allowed for %0 attribute">;
 def err_init_priority_object_attr : Error<
   "can only use 'init_priority' attribute on file-scope definitions "
   "of objects of class type">;
Index: lib/Sema/SemaDeclAttr.cpp
===================================================================
--- lib/Sema/SemaDeclAttr.cpp
+++ lib/Sema/SemaDeclAttr.cpp
@@ -254,7 +254,8 @@
   }
 
   if (StrictlyUnsigned && I.isSigned() && I.isNegative()) {
-    S.Diag(getAttrLoc(AI), diag::err_attribute_argument_negative) << AI;
+    S.Diag(getAttrLoc(AI), diag::err_attribute_requires_positive_integer)
+        << AI << /*non-negative*/ 1;
     return false;
   }
 
Index: lib/Sema/SemaStmtAttr.cpp
===================================================================
--- lib/Sema/SemaStmtAttr.cpp
+++ lib/Sema/SemaStmtAttr.cpp
@@ -304,7 +304,7 @@
     if (Val <= 0) {
       S.Diag(A.getRange().getBegin(),
              diag::err_attribute_requires_positive_integer)
-          << A;
+          << A << /* positive */ 0;
       return nullptr;
     }
     UnrollFactor = Val;
Index: test/SemaOpenCL/invalid-kernel-attrs.cl
===================================================================
--- test/SemaOpenCL/invalid-kernel-attrs.cl
+++ test/SemaOpenCL/invalid-kernel-attrs.cl
@@ -38,8 +38,8 @@
 kernel __attribute__((intel_reqd_sub_group_size(0))) void kernel15(){} // expected-error {{'intel_reqd_sub_group_size' attribute must be greater than 0}}
 kernel __attribute__((intel_reqd_sub_group_size(8))) __attribute__((intel_reqd_sub_group_size(16))) void kernel16() {}  //expected-warning{{attribute 'intel_reqd_sub_group_size' is already applied with different parameters}}
 
-__kernel __attribute__((work_group_size_hint(8,-16,32))) void neg1() {} //expected-error{{negative argument is not allowed for 'work_group_size_hint' attribute}}
-__kernel __attribute__((reqd_work_group_size(8,16,-32))) void neg2(){} // expected-error{{negative argument is not allowed for 'reqd_work_group_size' attribute}}
+__kernel __attribute__((work_group_size_hint(8,-16,32))) void neg1() {} //expected-error{{'work_group_size_hint' attribute requires a non-negative integral compile time constant expression}}
+__kernel __attribute__((reqd_work_group_size(8,16,-32))) void neg2(){} // expected-error{{'reqd_work_group_size' attribute requires a non-negative integral compile time constant expression}}
 
 // 4294967294 is a negative integer if treated as signed.
 // Should compile successfully, since we expect an unsigned.