Force mex to use LCC even with Visual Studio installed

If I install Matlab on a machine without a compatible version of Visual C++, it happily uses the bundled LCC to compile mex files, build Simulink models, and so on.

If Visual C++ is installed, it uses that compiler instead.

Fair enough, but I would like to be able to force it to use the bundled LCC, temporarily, even with VC++ installed. I would like this option so that I can run tests using LCC. I don't want to force downstream users to install Visual Studio just to run some silly Simulink model I wrote, and LCC sometimes does not work that well.

Of course, "mex -setup cpp" is useless, it just flat out doesn't give me the option. Tried this on a few different recent versions.