  We consider budget constrained combinatorial auctions where bidder $i$ has a
private value $v_i$, a budget $b_i$, and is interested in all the items in
$S_i$. The value to agent $i$ of a set of items $R$ is $|R \cap S_i| \cdot
v_i$. Such auctions capture adword auctions, where advertisers offer a bid for
ads in response to an advertiser-dependent set of adwords, and advertisers have
budgets. It is known that even of all items are identical and all budgets are
public it is not possible to be truthful and efficient. Our main result is a
novel auction that runs in polynomial time, is incentive compatible, and
ensures Pareto-optimality for such auctions when the valuations are private and
the budgets are public knowledge. This extends the result of Dobzinski et al.
(FOCS 2008) for auctions of multiple {\sl identical} items and public budgets
to single-valued {\sl combinatorial} auctions with public budgets.
