diff --git a/clang/include/clang/Basic/Diagnostic.td b/clang/include/clang/Basic/Diagnostic.td
index 21de05b707a58..503b833e63bbf 100644
--- a/clang/include/clang/Basic/Diagnostic.td
+++ b/clang/include/clang/Basic/Diagnostic.td
@@ -55,11 +55,11 @@ class DiagCategory<string Name> {
 }
 
 // Diagnostic Groups.
-class DiagGroup<string Name, list<DiagGroup> subgroups = []> {
+class DiagGroup<string Name, list<DiagGroup> subgroups = [], code docs = [{}]> {
   string GroupName = Name;
   list<DiagGroup> SubGroups = subgroups;
   string CategoryName = "";
-  code Documentation = [{}];
+  code Documentation = docs;
 }
 class InGroup<DiagGroup G> { DiagGroup Group = G; }
 //class IsGroup<string Name> { DiagGroup Group = DiagGroup<Name>; }
diff --git a/clang/include/clang/Basic/DiagnosticDocs.td b/clang/include/clang/Basic/DiagnosticDocs.td
index bf88d5d04567e..e9862422b4997 100644
--- a/clang/include/clang/Basic/DiagnosticDocs.td
+++ b/clang/include/clang/Basic/DiagnosticDocs.td
@@ -81,3 +81,9 @@ Diagnostic flags
 }];
 }
 
+defvar GCCWriteStringsDocs = [{
+**Note:** enabling this warning in C will change the semantic behavior of the
+program by treating all string literals as having type ``const char *``
+instead of ``char *``. This can cause unexpected behaviors with type-sensitive
+constructs like ``_Generic``.
+}];
diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
index 31f64f4eceb7c..0ee43fb8837a1 100644
--- a/clang/include/clang/Basic/DiagnosticGroups.td
+++ b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -847,7 +847,8 @@ def WritableStrings : DiagGroup<"writable-strings", [DeprecatedWritableStr]>;
 //
 // FIXME: Should this affect C++11 (where this is an error,
 //        not just deprecated) or not?
-def GCCWriteStrings : DiagGroup<"write-strings" , [WritableStrings]>;
+def GCCWriteStrings : DiagGroup<"write-strings" , [WritableStrings],
+                                GCCWriteStringsDocs>;
 
 def CharSubscript : DiagGroup<"char-subscripts">;
 def LargeByValueCopy : DiagGroup<"large-by-value-copy">;