diff --git a/security/Member.php b/security/Member.php
index a83a9d20e..927ae14c0 100644
--- a/security/Member.php
+++ b/security/Member.php
@@ -1820,6 +1820,37 @@ class Member_GroupSet extends ManyManyList {
 		}
 	}
 
+	public function removeAll() {
+		$base = ClassInfo::baseDataClass($this->dataClass());
+
+		// Remove the join to the join table to avoid MySQL row locking issues.
+		$query = $this->dataQuery();
+		$foreignFilter = $query->getQueryParam('Foreign.Filter');
+		$query->removeFilterOn($foreignFilter);
+
+		$selectQuery = $query->query();
+		$selectQuery->setSelect("\"{$base}\".\"ID\"");
+
+		$from = $selectQuery->getFrom();
+		unset($from[$this->joinTable]);
+		$selectQuery->setFrom($from);
+		$selectQuery->setOrderBy(); // ORDER BY in subselects breaks MS SQL Server and is not necessary here
+		$selectQuery->setDistinct(false);
+
+		// Use a sub-query as SQLite does not support setting delete targets in
+		// joined queries.
+		$delete = new SQLDelete();
+		$delete->setFrom("\"{$this->joinTable}\"");
+		// Use ManyManyList::foreignIDFilter() rather than the one in this class
+		// otherwise we end up selecting the wrong columns
+		$delete->addWhere(parent::foreignIDFilter());
+		$subSelect = $selectQuery->sql($parameters);
+		$delete->addWhere(array(
+			"\"{$this->joinTable}\".\"{$this->localKey}\" IN ($subSelect)" => $parameters
+		));
+		$delete->execute();
+	}
+
 	/**
 	 * Determine if the following groups IDs can be added
 	 *
diff --git a/tests/security/MemberTest.php b/tests/security/MemberTest.php
index 342a2da71..22753c4e1 100644
--- a/tests/security/MemberTest.php
+++ b/tests/security/MemberTest.php
@@ -377,6 +377,35 @@ class MemberTest extends FunctionalTest {
 		);
 	}
 
+	/**
+	 * Assertions to check that Member_GroupSet is functionally equivalent to ManyManyList
+	 */
+	public function testRemoveGroups()
+	{
+		$staffmember = $this->objFromFixture('Member', 'staffmember');
+
+		$staffgroup = $this->objFromFixture('Group', 'staffgroup');
+		$managementgroup = $this->objFromFixture('Group', 'managementgroup');
+
+		$this->assertTrue(
+			$staffmember->inGroups(array($staffgroup, $managementgroup)),
+			'inGroups() succeeds if a membership is detected on one of many passed groups'
+		);
+
+		$staffmember->Groups()->remove($managementgroup);
+		$this->assertFalse(
+			$staffmember->inGroup($managementgroup),
+			'member was not removed from group using ->Groups()->remove()'
+		);
+
+		$staffmember->Groups()->removeAll();
+		$this->assertEquals(
+			0,
+			$staffmember->Groups()->count(),
+			'member was not removed from all groups using ->Groups()->removeAll()'
+		);
+	}
+
 	public function testAddToGroupByCode() {
 		$grouplessMember = $this->objFromFixture('Member', 'grouplessmember');
 		$memberlessGroup = $this->objFromFixture('Group','memberlessgroup');