Cross compiling FreeBSD from a Linux based machine???

It was not clear to me if there was some provision for cross compiling 
the FreeBSD 'world' using
a Linux machine as a host.

I know that NetBSD makes everything using a very vanilla Makefile at the 
start to then compile
the NetBSD version of make, and then subsequently builds everything, 
compiler, standard unix
tool set, and kernel.

However, I didn't see that sort of setup in the FreeBSD environment. Is 
it a simple matter
of invoking or getting a 'bsd' style make program built first. Or is 
there more to it than that.

Thanks,
John Clark.