diff --git a/src/ORM/FieldType/DBDate.php b/src/ORM/FieldType/DBDate.php
index 4bb948350..2082ba22f 100644
--- a/src/ORM/FieldType/DBDate.php
+++ b/src/ORM/FieldType/DBDate.php
@@ -543,6 +543,24 @@ class DBDate extends DBField
         return $this->Format(self::ISO_DATE) === DBDatetime::now()->Format(self::ISO_DATE);
     }
 
+    /**
+     * Adjusts the current instance by the given adjustment, in a PHP `strtotime()` style date/time modifier.
+     *
+     * Example:
+     *
+     * <code>
+     * DBDatetime::now()->modify('+ 3 days')->Format()
+     * DBDatetime::now()->modify('-10 weeks')->Format()
+     * </code>
+     *
+     * @param string $adjustment PHP strtotime style
+     */
+    public function modify(string $adjustment): self
+    {
+        $modifiedTime = strtotime($adjustment, $this->getTimestamp());
+        return $this->setValue($modifiedTime);
+    }
+
     /**
      * Returns a date suitable for insertion into a URL and use by the system.
      *
diff --git a/tests/php/ORM/DBDateTest.php b/tests/php/ORM/DBDateTest.php
index b33cecced..5ea524b20 100644
--- a/tests/php/ORM/DBDateTest.php
+++ b/tests/php/ORM/DBDateTest.php
@@ -352,4 +352,34 @@ class DBDateTest extends SapphireTest
         $date = DBDate::create_field('Date', '2010-12-31');
         $this->assertEquals('2010-12-31T00:00:00+00:00', $date->Rfc3339());
     }
+
+    /**
+     * @param string $adjustment
+     * @param string $expected
+     * @dataProvider modifyProvider
+     */
+    public function testModify($adjustment, $expected)
+    {
+        /** @var DBDate $dateField */
+        $dateField = DBField::create_field('Date', '2019-03-03');
+        $result = $dateField->modify($adjustment)->URLDate();
+        $this->assertSame($expected, $result);
+    }
+
+    /**
+     * @return array[]
+     */
+    public function modifyProvider()
+    {
+        return [
+            ['+1 day', '2019-03-04'],
+            ['-1 day', '2019-03-02'],
+            ['+24 hours', '2019-03-04'],
+            ['-24 hours', '2019-03-02'],
+            ['+2 weeks', '2019-03-17'],
+            ['-2 weeks', '2019-02-17'],
+            ['+2 years', '2021-03-03'],
+            ['-2 years', '2017-03-03'],
+        ];
+    }
 }
diff --git a/tests/php/ORM/DBDatetimeTest.php b/tests/php/ORM/DBDatetimeTest.php
index ed0a4f3d1..defb31f9d 100644
--- a/tests/php/ORM/DBDatetimeTest.php
+++ b/tests/php/ORM/DBDatetimeTest.php
@@ -232,4 +232,39 @@ class DBDatetimeTest extends SapphireTest
         $date = DBDatetime::create_field('Datetime', '2010-12-31 16:58:59');
         $this->assertEquals('2010-12-31T16:58:59+00:00', $date->Rfc3339());
     }
+
+    /**
+     * @param string $adjustment
+     * @param string $expected
+     * @dataProvider modifyProvider
+     */
+    public function testModify($adjustment, $expected)
+    {
+        DBDatetime::set_mock_now('2019-03-03 12:00:00');
+        $result = DBDatetime::now()->modify($adjustment)->Rfc2822();
+        $this->assertSame($expected, $result);
+    }
+
+    /**
+     * @return array[]
+     */
+    public function modifyProvider()
+    {
+        return [
+            ['+1 day', '2019-03-04 12:00:00'],
+            ['-1 day', '2019-03-02 12:00:00'],
+            ['+24 hours', '2019-03-04 12:00:00'],
+            ['-24 hours', '2019-03-02 12:00:00'],
+            ['+2 weeks', '2019-03-17 12:00:00'],
+            ['-2 weeks', '2019-02-17 12:00:00'],
+            ['+2 years', '2021-03-03 12:00:00'],
+            ['-2 years', '2017-03-03 12:00:00'],
+            ['+35 minutes', '2019-03-03 12:35:00'],
+            ['-35 minutes', '2019-03-03 11:25:00'],
+            ['+3 hours', '2019-03-03 15:00:00'],
+            ['-3 hours', '2019-03-03 09:00:00'],
+            ['+59 seconds', '2019-03-03 12:00:59'],
+            ['-59 seconds', '2019-03-03 11:59:01'],
+        ];
+    }
 }