The answer to the first is a certain yes. There are laws against businesses forming monopolies in the United States. You can read up on the Sherman and Clayton antitrust acts from the 1890s and 1910s to start with. There is also considerable case law stemming from this legislation.
The answer to "should there be laws against monopolies" is a little more open. One theoretical justification for breaking up monopolies, is that in some cases monopolies cause economic inefficiencies. Look up "deadweight loss from monopoly pricing".
It's very complicated to measure any efficiencies or inefficiencies from tech monopolies, so I don't think there's a clear answer.
It's also not generally agreed upon that economic efficiency should be the goal of government, so there is a lot of room for debate on that question.
