While not germane to the use of LLVM itself, I firmly believe that the LLVM_DEFAULT Makevar should never be overridden. It is set in Mk/bsd.default-versions.mk and thus ought to be set by user choice. Please see: https://wiki.freebsd.org/HardcodedLLVMVersions#Ports_That_Redefine_LLVM_VERSION mcl