It's checked in a cmake function that builds up a list called `config_options`. But the check was appending to a list called `compile_options`, so the intended `-DLIBC_MATH=whatever` didn't end up on the actual compile command lines.
LLVM libc ========= This directory and its subdirectories contain source code for llvm-libc, a retargetable implementation of the C standard library. LLVM is open source software. You may freely distribute it under the terms of the license agreement found in LICENSE.txt.