  We present a new technique for tagging heavy-flavor jets with p_T > 500 GeV
called "mu_x tagging." Current track-based methods of b-jet tagging lose
efficiency and experience a large rise in fake rate in the boosted regime.
Using muons from B hadron decay, we combine angular information and jet
substructure to tag b jets, c jets, light jets, and "light-heavy" jets (those
containing B hadrons from gluon splitting). We find tagging efficiencies of
epsilon_b = 14%, epsilon_c = 6.5%, epsilon_{light-light} = 0.14%, and
epsilon_{light-heavy} = 0.5%, respectively, that are nearly independent of
transverse momentum at high energy. We demonstrate the usefulness of this new
scheme by examining the discovery potential for multi-TeV leptophobic Z-prime
bosons in the boosted-b-tagged dijet channel at the Large Hadron Collider.
