In this paper we present lightweight record-and-replay (RR). In contrast to traditional "fully deterministic" RR solutions, lightweight RR focuses on handling nondeterminism arising from thread communication for programs with concurrent, message-passing architectures. By decreasing nondeterminism in programs, lightweight RR decreases the number of intermittent failures in program's test suites. We evaluated the effectiveness of lightweight RR on Servo, a highly concurrent web browser. Our evaluation shows lightweight RR is effective at greatly reducing intermittent failures for some tests, but not others. Lightweight RR performance overhead remains a work in progress, but log sizes are quite small. We believe with further work lightweight RR could prove useful for lowering nondeterminism in programs at a negligible performance overhead.