[compiler-rt] running builtins test suite

I am trying to build and test the builtins library on 32-bit MIPS. There
doesn't seem to be a defined procedure for running the test suite.
There is a 'test' shell script in test/builtins/Unit but it seems to be outdated
and specific to darwin with hard-coded paths. Comments in
test/CMakeLists.txt suggest that builtins and BlockRunTime testsuites
have not yet been ported to lit framework.

Am I missing something?

If there is no present alternative, would it be okay to create a rudimentary
CTest setup to run the unit tests in builtins, as a stop-gap until the test
sources are modified for lit?