Five years ago I posted a video of Paul Simon singing his "An American Tune." I noted that the melody was based on Tom Glazer's "Because All Men Are Brothers," and in turn on Bach's great passion chorus O Haupt voll Blut und Wunden from his St. Matthew Passion. The clip above is of O Haupt, sung by the choir of Concentus Musicus Wien under the direction of Nikolaus Harnoncourt.
As was also mentioned in my Simon post, Bach got the melody for O Haupt from a sixteenth century composition by Hans Leo Hassler. O Haupt is also the basis for the English passion hymn "O Sacred Head Sore Wounded."