llvm-lit /path/to/test/src should now invoke tests across all configurations. If this looks helpful, I could port other components.
For example
➜ bin/llvm-lit -vv ~/Src/u/compiler-rt/test/asan/TestCases/alloca_big_alignment.cpp -- Testing: 4 tests, 4 workers -- PASS: AddressSanitizer-i386-linux-dynamic :: TestCases/alloca_big_alignment.cpp (1 of 4) PASS: AddressSanitizer-x86_64-linux-dynamic :: TestCases/alloca_big_alignment.cpp (2 of 4) PASS: AddressSanitizer-i386-linux :: TestCases/alloca_big_alignment.cpp (3 of 4) PASS: AddressSanitizer-x86_64-linux :: TestCases/alloca_big_alignment.cpp (4 of 4) Testing Time: 0.21s Expected Passes : 4