diff --git a/sale_order_discount/__init__.py b/sale_order_discount/__init__.py
new file mode 100644
index 00000000000..0650744f6bc
--- /dev/null
+++ b/sale_order_discount/__init__.py
@@ -0,0 +1 @@
+from . import models
diff --git a/sale_order_discount/__manifest__.py b/sale_order_discount/__manifest__.py
new file mode 100644
index 00000000000..83c62ae4e39
--- /dev/null
+++ b/sale_order_discount/__manifest__.py
@@ -0,0 +1,10 @@
+{
+    'name': "Sale Order Discount",
+    'version': "1.0",
+    'category': "Sales",
+    'description': "Updates global discount when order lines are changed",
+    'depends': ['sale_management'],
+    'installable': True,
+    'author': "jakan",
+    'license': "LGPL-3",
+}
diff --git a/sale_order_discount/models/__init__.py b/sale_order_discount/models/__init__.py
new file mode 100644
index 00000000000..6aacb753131
--- /dev/null
+++ b/sale_order_discount/models/__init__.py
@@ -0,0 +1 @@
+from . import sale_order
diff --git a/sale_order_discount/models/sale_order.py b/sale_order_discount/models/sale_order.py
new file mode 100644
index 00000000000..9d8457e158f
--- /dev/null
+++ b/sale_order_discount/models/sale_order.py
@@ -0,0 +1,47 @@
+import re
+from odoo import api, models
+from odoo.exceptions import UserError
+
+
+class SaleOrder(models.Model):
+    _inherit = 'sale.order'
+
+    @api.onchange('order_line')
+    def _onchange_recalculate_global_discount(self):
+        discount_lines = self.env['sale.order.line']
+        for line in self.order_line:
+            if line._is_global_discount():
+                discount_lines += line
+
+        if not discount_lines:
+            return
+
+        product_lines = self.env['sale.order.line']
+        for line in self.order_line:
+            if not line._is_global_discount():
+                product_lines += line
+
+        if not product_lines:
+            self.order_line -= discount_lines
+            return
+
+        subtotal = 0
+        for line in product_lines:
+            subtotal += line.price_subtotal
+
+        for discount_line in discount_lines:
+            match = re.search(r"(\d+(?:\.\d+)?)%", discount_line.name)
+            if match:
+                percent = float(match.group(1))
+                discount_line.price_unit = -(subtotal * percent / 100)
+
+    @api.constrains('order_line')
+    def _check_single_global_discount(self):
+        for order in self:
+            discounts = order.order_line.filtered(
+                lambda l: l._is_global_discount()
+            )
+            if len(discounts) > 1:
+                raise UserError(
+                    "Only one global discount is allowed per order."
+                )