  We construct the gravity duals of large N supersymmetric gauge theories
defined on squashed five-spheres with SU(3) x U(1) symmetry. These five-sphere
backgrounds are continuously connected to the round sphere, and we find a
one-parameter family of 3/4 BPS deformations and a two-parameter family of
(generically) 1/4 BPS deformations. The gravity duals are constructed in
Euclidean Romans F(4) gauged supergravity in six dimensions, and uplift to
massive type IIA supergravity. We holographically renormalize the Romans
theory, and use our general result to compute the renormalized on-shell actions
for the solutions. The results agree perfectly with the large N limit of the
dual gauge theory partition function, which we compute using large N matrix
model techniques. In addition we compute BPS Wilson loops in these backgrounds,
both in supergravity and in the large N matrix model, again finding precise
agreement. Finally, we conjecture a general formula for the partition function
on any five-sphere background, which for fixed gauge theory depends only on a
certain supersymmetric Killing vector.
