  We explore the formation and evolution of the black hole X-ray binary system
M33 X-7. In particular, we examine whether accounting for systematic errors in
the stellar parameters inherent to single star models, as well as the
uncertainty in the distance to M33, can explain the discrepancy between the
observed and expected luminosity of the ~70 solar masses companion star. Our
analysis assumes no prior interactions between the companion star and the black
hole progenitor. We use four different stellar evolution codes, modified to
include a variety of current stellar wind prescriptions. For the models
satisfying the observational constraints on the donor star's effective
temperature and luminosity, we recalculate the black hole mass, the orbital
separation, and the mean X-ray luminosity. Our best model, satisfying
simultaneously all observational constraints except the observationally
inferred companion mass, consists of a ~13 solar masses black hole and a ~54
solar masses companion star. We conclude that a star with the observed mass and
luminosity can not be explained via single star evolution models, and that a
prior interaction between the companion star and the black hole progenitor
should be taken into account.
