The FreeBSD and GNUTools drivers support -fsanitize arguments bypassing -nodefaultlibs. With https://reviews.llvm.org/D24048, Darwin will support that behavior as well.
To make this a little less magical and behind the curtain this warning will fire when -nodefaultlibs is used with sanitizer arguments.
What about something like: "-nodefaultlibs does not skip sanitizer runtime libs when used with -fsanitize." ?