A brightness- and power-scalable polarization beam-combining scheme for high-power, broad-area semiconduc-tor laser diodes is investigated numerically and experimentally. To achieve the beam combining, we employ Lyot-filtered optical reinjection from an external cavity, which forces lasing of the individual diodes on interleavedfrequency combs with overlapping envelopes and enables a high optical coupling efficiency. Unlike conventionalspectral beam-combining schemes with diffraction gratings, the optical coupling efficiency is insensitive to ther-mal drifts of laser wavelengths. This scheme can be used for efficient coupling of a large number of laser diodesand paves the way toward using broad-area laser diode arrays for cost-efficient material processing, which requireshigh-brilliance emission and optical powers in the kW regime.