In a large pitcher, pour tequila, orange liqueur, freshly squeezed lime juice, and agave syrup. Stir well until the agave syrup is fully mixed in.
Cover the pitcher and place it in the refrigerator for at least one hour to chill.
When ready to serve, add ice to the pitcher and stir the chilled Margarita mix again. Rim each glass with salt or Tajín and pour the cocktails, adding some ice if needed. Garnish with a lime wedge and serve immediately.