diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -576,10 +576,10 @@
   "thread-local storage is not supported for the current target">;
 
 def warn_maybe_falloff_nonvoid_function : Warning<
-  "control may reach end of non-void function">,
+  "not all control paths in this function return a value; non-void function must return a value">,
   InGroup<ReturnType>;
 def warn_falloff_nonvoid_function : Warning<
-  "control reaches end of non-void function">,
+  "function does not return a value; non-void function must return a value">,
   InGroup<ReturnType>;
 def err_maybe_falloff_nonvoid_block : Error<
   "control may reach end of non-void block">;