This isn't really a linker flag and worked only because C/C++ compiler is usually used as linker. This is backed by my own study of LLVM's code as well as this reply from Flang's dev: https://discourse.llvm.org/t/flang-working-as-linker/87133/5 Approved by: bapt (portmgr) Differential Revision: https://reviews.freebsd.org/D51116