Cream butter and cream cheese until fluffy; gradually blend in sugar. Stir together flour and salt; stir into creamed mixture. Cover; chill dough several hours or overnight.
Preheat oven to 375 degrees F (190 degrees C).
Divide dough into thirds. On lightly floured surface, roll out dough, one section at a time. (Keep the other sections refrigerated.) Cut out with cookie cutter to desired shapes.
Place on ungreased cookie sheet. Bake until firm, but not brown, about 12 minutes. If desired, sift additional confectioners' sugar over slightly warm cookies.