You can execute anything you can do in the shell in your makefile so you can just insert a one liner. Note that quoting conventions differ on Win32 and *nix so this is not entirely portable.

#define  VERSION_STRING   "Foo built Sun Dec 16 21:40:50 2007"

version:
    perl -pi.old -e 's/(VERSION_STRING[\w\s\"]+built )[^\"]+/$$1.local
+time/e' Makefile
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