[plt-scheme] internal scheme_memcpy?

I would like to use the C function memcpy to copy chunks of memory Im 
using with ffi. On linux this works:

(define memcpy (get-ffi-obj "memcpy" #f
                (_fun _pointer _pointer _int -> _pointer)))

Probably just because libc is linked in with mzscheme but on windows I 
get an error because memcpy is not found. Is there a standard internal 
scheme function that does the same thing as memcpy I can use? Otherwise 
I guess I could just write memcpy in scheme with ptr-set!/ptr-ref.