diff --git a/llvm/docs/ReleaseNotes.rst b/llvm/docs/ReleaseNotes.rst
--- a/llvm/docs/ReleaseNotes.rst
+++ b/llvm/docs/ReleaseNotes.rst
@@ -231,6 +231,17 @@
 
 Changes to Sanitizers
 ---------------------
+* For users of weak overrides on Darwin, the dynamic linker (dyld) will only
+  consider symbols from other mach-o modules (dylibs and main executable), which
+  themselves contain at least one weak symbol. A consequence of this is that if
+  your main program contains an intended override of a sanitizer weak reference,
+  then it must contain at least one weak symbol. (NB: This symbol may be the
+  intended override itself). ::
+
+    Example:
+      __attribute__((weak,unused)) unsigned __enableOverrides;
+    or:
+      __attribute__((weak)) void __asan_on_error(void) {...}
 
 Other Changes
 -------------