This is a set of individual patches, which contain all the customizations to llvm/clang currently in the FreeBSD base system. These can be applied in alphabetical order to a pristine llvm/clang 3.4 release source tree, for example by doing: svn co https://llvm.org/svn/llvm-project/llvm/tags/RELEASE_34/final llvm-3.4-final svn co https://llvm.org/svn/llvm-project/cfe/tags/RELEASE_34/final llvm-3.4-final/tools/clang cd llvm-3.4-final for p in /usr/src/contrib/llvm/patches/patch-*.diff; do patch -p0 -f -F0 -E -i $p -s || break done A number of these consist of hand-written modifications, specifically for FreeBSD, while most others are cherry pickings off the llvm and clang trunks. When a new version of llvm/clang is eventually imported, those latter ones will largely disappear.