Modified Condition/Decision Coverage (MC/DC) is a comprehensive code coverage criterion that is extremely useful in weeding out hidden bugs and guaranteeing robustness. MC/DC is very handy for average developers as well as those in the safety-critical embedded Industrial, Automotive, and Aviation markets where it is required. In this talk, I will show how we extended LLVM’s Source-based Code Coverage infrastructure to support MC/DC by tracking test vectors, which represent the sequential true/false evaluation of conditions through a boolean expression.