disabling horizontal scroll on an iPhone website

I know I am a little late to the party, but I was having this same issue and solved it by adding:

body, html{
    overflow-x: hidden;
}

Hopefully this will help someone else!

Add overflows on your body like this:

body    {
        font: 12px/20px "Helvetica neue", Helvetica, Arial, sans-serif;
        font-weight: normal;
        overflow: hidden;
        overflow-y: auto;
        }

And yes stay with this:

<meta name="viewport" content="width=device-width">