As you can see, HeinOnline contains resources called the "U.S. Federal Legislative History Library," which you can click on from the main page. This database includes both Nancy P. Johnson's Sources of Compiled Legislative Histories, as well as legislative history published by the Government Publishing Office.
Once in the database you can search by Popular Name or by Public Law Number to find legislative histories for federal laws from the 1st Congress to the 113 Congress.
