diff --git a/sys/dev/pci/pci.c b/sys/dev/pci/pci.c
--- a/sys/dev/pci/pci.c
+++ b/sys/dev/pci/pci.c
@@ -429,6 +429,10 @@
     &pci_enable_mps_tune, 1,
     "Enable tuning of MPS(maximum payload size)." );
 
+static bool no_legacy_reroute = false;
+SYSCTL_BOOL(_hw_pci, OID_AUTO, no_legacy_reroute, CTLFLAG_RWTUN,
+    &no_legacy_reroute, 0, "Disable INTx re-routing.");
+
 static int
 pci_has_quirk(uint32_t devid, int quirk)
 {
@@ -4182,7 +4186,8 @@
 		 * If the re-route fails, then just stick with what we
 		 * have.
 		 */
-		pci_assign_interrupt(bus, dev, 1);
+		if (! no_legacy_reroute)
+			pci_assign_interrupt(bus, dev, 1);
 	}
 
 	if (pci_usb_takeover && pci_get_class(dev) == PCIC_SERIALBUS &&