Preheat your oven to 350°F (175°C).
In a large bowl, combine sliced peaches, granulated sugar, lemon juice, and cinnamon.
Pour the peach mixture into a greased 9x13 inch baking dish.
In another bowl, mix flour, rolled oats, brown sugar, and salt.
Stir in melted butter until crumbly.
Evenly sprinkle the crumble topping over the peach mixture.
Bake for 35-40 minutes until the topping is golden brown.
Allow to cool for 10 minutes before serving.
Serve warm, optionally with vanilla ice cream or whipped cream.