  In this paper, we study the behavior of $\Upsilon_K(t)$ under the cabling
operation, where $\Upsilon_K(t)$ is the knot concordance invariant defined by
Ozsv\'ath, Stipsicz, and Szab\'o, associated to a knot $K\subset S^3$. The main
result is an inequality relating $\Upsilon_K(t)$ and $\Upsilon_{K_{p,q}}(t)$,
which generalizes the inequalities of Hedden and Van Cott on the
Ozsv\'ath-Szab\'o $\tau$-invariant. As applications, we give a computation of
$\Upsilon_{(T_{2,-3})_{2,2n+1}}(t)$ for $n\geq 8$, and we also show that the
set of iterated $(p,1)$-cables of $Wh^{+}(T_{2,3})$ for any $p\geq 2$ span an
infinite-rank summand of topologically slice knots.
