This has probably been discussed before but I think that this warning should be suppressed when -S is used and the "input" is for a later phase. For example: /local/llvmpb_config/install/bin/clang -target mipsel-linux-gnu fp16instrins.c -o fp16instrins -EL -mips16 -fPIC -gcc-toolchain $MIPS -lm -S clang: warning: -lm: 'linker' input unused