  The recent observation of a 125 GeV neutral Higgs boson ($H_{\rm obs}$)
provides additional input for charged Higgs boson searches in the $H^\pm \to
W^\pm H_{\rm obs}$ decay channel at the Large Hadron Collider (LHC). We
reassess the discovery potential in this channel, which is important for
$H^\pm$ heavier than the top quark mass. When $H_{\rm obs}$ decays to a
$b\bar{b}$ pair, knowledge of the Higgs mass aids in the kinematic selection of
signal events. We perform a signal-to-background analysis to demonstrate the
LHC prospects for charged Higgs discovery in the resulting channel $pp\to
t(\bar{b})H^-\to \ell^\pm\nu_\ell jj bb\bar{b}(\bar{b})$+h.c. for standard (300
fb$^{-1}$) and high (3000 fb$^{-1}$) luminosities at design energy,
$\sqrt{s}=14 {\rm TeV}$. We find that regions of the parameter space of several
two-Higgs doublet models, consistent with constraints from LHC Higgs searches
and $b$-physics observables, are testable in this channel.
