LLVM  Clang, a BSD licenced compiler, is an alternative base compiler, with the general intention of it becoming the official FreeBSD base compiler.

On June 9th, we are importing clang/LLVM into FreeBSD HEAD. We are going to import clang/LLVM sources and put those into contrib/llvm (~45MB) and the build infrastructure for it (lib/clang and usr.bin/clang). There’s also a small patch to hook it into the build.

LLVM Clang will bring some great benefits

More over LLVM Clang on FreeBSD can be heard in an interview with Roman Divácký and Ed Schouten at BSD Can 2010: BSD Talk 191.