Preheat oven to 425 degrees. In a small bowl, combine minced garlic, chopped rosemary, fennel seeds, salt and one tablespoon olive oil. Season with fresh ground black pepper.
Rub the garlic mixture over the pork tenderloin. In a large baking dish, place the rosemary sprigs and set the tenderloin on top. Wrap the bacon slices around the tenderloin, making sure to tuck the ends of the bacon slices underneath the tenderloin. Place the halved garlic heads around the pork and drizzle the garlic with the remaining olive oil.
Roast until an instant thermometer reads 145 degrees when inserted in the thickest part of the tenderloin, about 40-45 minutes. Check right at 40 minutes, so as to not overcook the pork. Transfer to a cutting board and let the meat rest for 10 minutes before slicing.