Dimensional reductions of supergravity theories on spheres play a central role in the gauge/gravity correspondence. Prominent examples are the reductions of eleven-dimensional supergravity on S7 and type IIB supergravity on S5 which are dual to ABJM and N=4 SYM theories, respectively. In this talk we present a new duality between massive IIA supergravity on S6 and super Chern-Simons-matter theories, and describe RG flows holographically in terms of domain-wall and black hole solutions in the gravity side.