Cleanly setting C compiler options when building RTS

Hello all, I was interested in building the GHC RTS with GCC's AddressSanitizer and Ubsan enabled. What I want to do very specifically is to pass "-fsanitize=address -fsanitize=undefined" when compiling the RTS. What's the "correct" way to set this up in the build system? Is there a configure flag? Do I need to change the Shake script? Thanks, ~Siddharth