  The discovery via gravitational waves of binary black hole systems with total
masses greater than $60M_\odot$ has raised interesting questions for stellar
evolution theory. Among the most promising formation channels for these systems
is one involving a common envelope binary containing a low metallicity, core
helium burning star with mass $\sim 80-90M_\odot$ and a black hole with mass
$\sim 30-40M_\odot$. For this channel to be viable, the common envelope binary
must eject more than half the giant star's mass and reduce its orbital
separation by as much as a factor of 80. We discuss issues faced in numerically
simulating the common envelope evolution of such systems and present a 3D AMR
simulation of the dynamical inspiral of a low-metallicity red supergiant with a
massive black hole companion.
