A rail support system includes a clamp side having a channel to engage around a post; an extension curved around the channel; a first bar engaged with the extension; a handle attached to the first bar; and a second bar attached to the first bar via a lateral connector; pivoting the handle causes the second bar to apply pressure to the second side of the channel; a cradle side having an arm attached to the channel and extending away therefrom; and a cradle support attached to and extending away from the arm, the cradle support being vertically adjustable relative to the channel; the cradle support is to receive a rail; the clamp side is to secure to the post while the cradle side is to engage with the rail such that the post and the rail are held in position for welding together.