We are developing a low-latency hardware trigger processor for the Monitored Drift Tube system in the Muon spectrometer. The processor will fit candidate Muon tracks in the drift tubes in real time, improving significantly the momentum resolution provided by the dedicated trigger chambers. We present a novel pure-FPGA implementation of a Legendre transform segment finder, an associative-memory alternative implementation, an ARM (Zynq) processor-based track fitter, and compact ATCA carrier board architecture. The ATCA architecture is designed to allow a modular, staged approach to deployment of the system and exploration of alternative technologies.