The way the LIT RUN command is currently constructed ( %run not --crash %t ) causes the test failure on devices - since 'not' is a LLVM built command, not available on devices. Changing the command to read 'not --crash %run %t' fixes it, as 'not' now executes on the host running the test. rdar://115914588 Co-authored-by: Mariusz Borsa <m_borsa@apple.com>