Preheat oven to 425°. In a small bowl, combine the mustard, garlic, pepper, garlic salt and onion salt; brush over tenderloin. Place in a shallow roasting pan. Bake, uncovered, until meat reaches desired doneness (for medium-rare, a thermometer should read 135°; medium, 140°; medium-well, 145°), 45 minutes.
Remove tenderloin from pan; let stand for 10-15 minutes before slicing. Meanwhile, add broth to pan drippings, stirring to loosen browned bits; heat through. Serve with sliced beef.