  Recently the observationally derived stellar-wind mass-loss rates for
Wolf-Rayet stars, or massive naked helium stars, have been revised downwards by
a substantial amount. We present evolutionary calculations of helium stars
incorporating such revised mass-loss rates, as well as mass transfer to a close
compact binary companion. Our models reach final masses well in excess of 10
Msun, consistent with the observed masses of black holes in X-ray binaries.
This resolves the discrepancy found with previously assumed high mass-loss
rates between the final masses of stars which spend most of their
helium-burning lifetime as Wolf-Rayet stars (about 3 Msun) and the minimum
observed black hole masses (6 Msun). Our calculations also suggest that there
are two distinct classes of progenitors for Type Ic supernovae: one with very
large initial masses (> 35 Msun), which are still massive when they explode and
leave black hole remnants, and one with moderate initial masses (about 12 - 20
Msun) undergoing binary interaction, which end up with small pre-explosion
masses and leave neutron star remnants.
