Cut a horizontal slit in the pork tenderloin, leaving the halves attached. Rub tenderloin with olive oil.
Insert garlic into the slit and on onto the fatty part of pork. Press thyme and rosemary into slit. Sprinkle tenderloin with salt and pepper.
Preheat an outdoor grill for medium-high heat.
Lightly oil the grill grate. Place pork on grill. Cook approximately 1 hour, turning every 15 minutes, to a minimum internal temperature of 145 degrees F (63 degrees C).
