HSghc-prim-0.3.1.0.o: unknown symbol 'memcpy'

[M Farkas-Dyck]

I just built stock ghc 7.8.1 against musl on Linux x86_64. I get this:

$ ghci
GHCi, version 7.8.1: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... ghc:
/lib/ghc-7.8.1/ghc-prim-0.3.1.0/HSghc-prim-0.3.1.0.o: unknown symbol
`memcpy'
ghc: unable to load package `ghc-prim'
$

memcpy is defined in /lib/libc.a; how can I link it in? I tried -lc
and -opt-lc options to ghci, in vain.