Preheat the oven to 300 degrees F (150 degrees C).
Rub pork loin with olive oil and place in a roasting pan. Drape slices of bacon over the top. Combine chicken stock, rosemary, thyme, basil, sage, and garlic; pour over roast. Place onions around the sides; cover with a lid or aluminum foil.
Bake in the preheated oven for 1 hour and 30 minutes. Remove the lid or foil, and continue to bake for 30 minutes, or until bacon is browned. An instant-read thermometer inserted into the center should read 145 degrees F (63 degrees C).