  We present a formula describing the asymptotics of a class of multivariate
orthogonal polynomials with hyperoctahedral symmetry as the degree tends to
infinity. The polynomials under consideration are characterized by a factorized
weight function satisfying certain analyticity assumptions. As an application,
the large-degree asymptotics of the Koornwinder-Macdonald BC_N-type
multivariate Askey-Wilson polynomials is determined.
