In the last 15 years, informality in the Brazilian labor market has been rising steadily, having stabilized in the last two years around 60% of the economically active population. The magnitude of this phenomenon is impressive not only for its intensity but also for its persistence, leading to an inevitable question: what is happening and why? Labor market institutions are usually pointed as one of the main causes of informality and it is frequently argued that their poor design would be generating incentives towards informality both for workers and employers. The objective of this work its to contribute for the debate analyzing the effects of these institutions on the informality degree, unemployment and welfare of the economy. To do so, I develop a matching model with two sectors - formal and informal - where workers and firms negotiate wages (through a Nash bargain) and the main institutional characteristics of the Brazilian labor market are included. The model is numerically solved, what allows investigating not only qualitative but also quantitative effects of policy experiments. From the results obtained with these exercises is possible to observe, for instance, that variations in the dismissal costs have more significant impacts on the informality degree and equilibrium unemployment than reductions in non-wage costs of labor. Besides this formal analysis, a review of the relevant literature and of the Brazilian labor legislation is made.