Eilish had switched up her look, wearing a baggy sweater and oversized shorts, while her brother wore a darker t-shirt and dark pants. Related: Billie ... a Merry Little Christmas," joined by ...

Billie Eilish is well-prepared for the holiday season. The singer closed out her five-night run at the Kia Forum in Los Angeles on Saturday (Dec. 21) with a cover of the Christmas standard "O Holy ...