The GNU/HURD is also using the libc. Therefor, endian.h should be included, not machine/endian.h. See full build log https://buildd.debian.org/status/fetch.php?pkg=llvm-toolchain-3.3&arch=hurd-i386&ver=1%3A3.3~%2Brc3-1~exp1&stamp=1370358869