Compile XNU

Anyone successfully compile XNU on an intel mac? I keep running into the following error:

== Making relpath for i386 ==
Pre-build setup...
/bin/rm -f /tmp/relpath.build/derived_src/TrustedPrecomps.txt
Building...
/usr/bin/cc -arch i386 -Os -Wmost -g -fno-common -I/tmp/relpath.build/ProjectHeaders -I -I -I/tmp/relpath.build/derived_src -I. -pipe -c -o /tmp/relpath.build/objects-optimized/relpath.i386.o relpath.c
cc: installation problem, cannot exec `cc1': No such file or directory
make: *** [/tmp/relpath.build/objects-optimized/relpath.i386.o] Error 1

I've followed the instructions carefully from Apple's Developer site, but keep having this error. Any ideas?

Never mind- I figured it out. I recompiled XNU with -Os to see if it speeds anything up (it should at least minutely!), also disabled kernel debugging. Little risky, but fun.

Update- I've definitely noticed a little speed increase, after I cleared the kernel cache and let it rebuild, of course.