llvm way only tests?

Hi all, what is the magic incantation for running tests only when the llvm tools (e.g. `opt`) are around? I am currently declaring the test as test('T15155l', [ only_ways(llvm_ways), ], run_command, ['$MAKE -s --no-print-directory T15155l']) but it won't be included neither in the optasm builds (which is okay) nor in the llvm builds (gets skipped unexpetedly) I looked at the other test which are declared similarly, and they behave just like mine. What I am doing wrong? Thanks, Gabor