I tried to build LLVM/Clang from git today on my Gentoo box and I ended up with this: [ 41%] Generating kmp_i18n_id.inc message-converter.pl: (x) /etc/lsb-release: There is no DISTRIB_RELEASE: message-converter.pl: (x) DISTRIB_ID="Gentoo" message-converter.pl: (x) (eof) It turned out that in order to build upstream LLVM/Clang the /etc/lsb-release file must look at least like that: DISTRIB_ID="Gentoo" DISTRIB_RELEASE="" DISTRIB_CODENAME="" DISTRIB_DESCRIPTION="" Reproducible: Always