We report on the development and construction of a new fiber-fed, red-optical, high-precision radial-velocity spectrograph for one of the twin 6.5m Magellan Telescopes in Chile. MAROON-X will be optimized to find and characterize rocky planets around nearby M dwarfs with an intrinsic per measurement noise floor below 1 m/s. The instrument is based on a commercial echelle spectrograph customized for high stability and throughput. A microlens array based pupil slicer and double scrambler, as well as a rubidium-referenced etalon comb calibrator will turn this spectrograph into a high-precision radial-velocity machine. MAROON-X will undergo extensive lab tests in the second half of 2016.