diff --git a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Control.java b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Control.java
index a162c1ce6ea..48c50564a48 100644
--- a/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Control.java	
+++ b/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Control.java	
@@ -3353,7 +3353,10 @@ public void setBounds (Rectangle rect) {
  * Thus, reduce the control size in case it would not fit anyway
  */
 private void fitInParentBounds(Rectangle boundsInPixels, int zoom) {
-	if (parent == null) {
+	if (parent == null || this instanceof Shell) {
+		// A Shell is a geometric top-level element and must not be fit into any
+		// logical parent's bounds — even if it has another Shell set as parent
+		// (which denotes an owner relationship, not geometric containment).
 		return;
 	}
 	Rectangle parentBoundsInPixels = parent.getBoundsInPixels();
diff --git a/tests/org.eclipse.swt.tests/JUnit Tests/org/eclipse/swt/tests/junit/Test_org_eclipse_swt_widgets_Shell.java b/tests/org.eclipse.swt.tests/JUnit Tests/org/eclipse/swt/tests/junit/Test_org_eclipse_swt_widgets_Shell.java
index bebbe450e8d..b660734626e 100644
--- a/tests/org.eclipse.swt.tests/JUnit Tests/org/eclipse/swt/tests/junit/Test_org_eclipse_swt_widgets_Shell.java	
+++ b/tests/org.eclipse.swt.tests/JUnit Tests/org/eclipse/swt/tests/junit/Test_org_eclipse_swt_widgets_Shell.java	
@@ -821,6 +821,33 @@ public void test_setSizeLorg_eclipse_swt_graphics_Point() {
 	}
 }
 
+// See https://github.com/eclipse-platform/eclipse.platform.swt/issues/3597
+@Test
+public void test_setSize_ownedShellNotConstrainedByOwnerBounds() throws InterruptedException {
+	shell.setSize(500, 500);
+	shell.open();
+
+	int ownerHeight = shell.getSize().y;
+	int ownerWidth = shell.getSize().x;
+	testShell.open();
+
+	// Make shell vertically exceed parent shell bounds
+	int requestedHeight = 100;
+	testShell.setLocation(0, ownerHeight - requestedHeight + 1);
+	testShell.setSize(200, requestedHeight);
+	SwtTestUtil.processEvents(10000, () -> testShell.getSize().y == requestedHeight);
+	assertEquals(requestedHeight, testShell.getSize().y,
+			"Owned Shell height must not be constrained by owner Shell bounds");
+
+	// Make shell horizontally exceed parent shell bounds
+	int requestedWidth = 100;
+	testShell.setLocation(ownerWidth - requestedWidth + 1, 0);
+	testShell.setSize(requestedWidth, 200);
+	SwtTestUtil.processEvents(10000, () -> testShell.getSize().x == requestedWidth);
+	assertEquals(requestedWidth, testShell.getSize().x,
+			"Owned Shell width must not be constrained by owner Shell bounds");
+}
+
 private void assertShellProperlySized(Shell shell, Point expectedSize) {
 	int tolerance = shell.getZoom() != 100 ? 1 : 0;
 	Point actualSize = shell.getSize();