We all know what Bill Belichick's wearing on Super Bowl Sunday (hoodie) -- but his girlfriend Linda Holliday is going with A LOT more flair ... with a custom crystal outfit, and TMZ Sports has the pics!
Linda hit up Leah Miller at Bella Artistry who makes custom Swarovski crystal fashion items for a TON of athletes and their significant others ... and ordered up some fresh gear for SBLII.
Holliday will be wearing a special blazer with her BF's last name spelled out across the back and his initials on the arm.