The C11 standard introduced atomic types and operations, with an accompanying memory model, to enable the use of shared variables in concurrent programs. In this thesis, I demonstrate how compilers can be tested, in a way that is deterministic and covers the entire set of atomic operations, to ensure they correctly implement C11 atomics and the C11 memory model.  I use a large set of short concurrent programs (”litmus tests”), generated from a model written in a specification language and based on a formalized C11 memory model. Each test program is compiled and run with a model checker, to determine the possible outcomes; any program with an outcome that is possible after compilation but not allowed by C11 is a failed test case. As an alternative to model checking, I also test a nondeterministic, hardware-based method for running tests, but I find that this method is too inaccurate to be useful.  I test IAR and gcc compilers for Arm and RISC-V; all of these compilers pass all tests. Out of three compilers with purposefully inserted bugs, all are correctly identified as faulty. This testing process thus shows some promise, but further evaluation is needed.