Index: sys/dev/efidev/efirt.c
===================================================================
--- sys/dev/efidev/efirt.c
+++ sys/dev/efidev/efirt.c
@@ -34,6 +34,7 @@
 
 #include <sys/param.h>
 #include <sys/efi.h>
+#include <sys/eventhandler.h>
 #include <sys/kernel.h>
 #include <sys/linker.h>
 #include <sys/lock.h>
@@ -41,6 +42,7 @@
 #include <sys/mutex.h>
 #include <sys/clock.h>
 #include <sys/proc.h>
+#include <sys/reboot.h>
 #include <sys/rwlock.h>
 #include <sys/sched.h>
 #include <sys/sysctl.h>
@@ -95,6 +97,7 @@
 
 static int efi_enter(void);
 static void efi_leave(void);
+static int _efi_reset_system(enum efi_reset);
 
 static int
 efi_status_to_errno(efi_status status)
@@ -106,6 +109,10 @@
 }
 
 static struct mtx efi_lock;
+static SYSCTL_NODE(_hw, OID_AUTO, efi, CTLFLAG_RWTUN, NULL, "EFI");
+static bool efi_poweroff = true;
+SYSCTL_BOOL(_hw_efi, OID_AUTO, poweroff, CTLFLAG_RWTUN, &efi_poweroff, 0,
+    "If true, use EFI runtime services to shutdown in preference to ACPI");
 
 static bool
 efi_is_in_map(struct efi_md *map, int ndesc, int descsz, vm_offset_t addr)
@@ -126,6 +133,19 @@
 	return (false);
 }
 
+static void
+efi_shutdown_final(void *dummy __unused, int howto)
+{
+
+	/*
+	 * On some systems, ACPI S5 is missing or does not function properly.
+	 * When present, shutdown via EFI Runtime Services instead, unless
+	 * disabled.
+	 */
+	if ((howto & RB_POWEROFF) != 0 && efi_poweroff)
+		(void)_efi_reset_system(EFI_RESET_SHUTDOWN);
+}
+
 static int
 efi_init(void)
 {
@@ -214,6 +234,12 @@
 	}
 #endif
 
+	/*
+	 * We use SHUTDOWN_PRI_LAST - 1 to trigger after IPMI, but before ACPI.
+	 */
+	EVENTHANDLER_REGISTER(shutdown_final, efi_shutdown_final, NULL,
+	    SHUTDOWN_PRI_LAST - 1);
+
 	return (0);
 }
 
@@ -410,8 +436,8 @@
 	return (error);
 }
 
-int
-efi_reset_system(void)
+static int
+_efi_reset_system(enum efi_reset type)
 {
 	struct efirt_callinfo ec;
 
@@ -420,7 +446,7 @@
 	bzero(&ec, sizeof(ec));
 	ec.ec_name = "rt_reset";
 	ec.ec_argcnt = 4;
-	ec.ec_arg1 = (uintptr_t)EFI_RESET_WARM;
+	ec.ec_arg1 = (uintptr_t)type;
 	ec.ec_arg2 = (uintptr_t)0;
 	ec.ec_arg3 = (uintptr_t)0;
 	ec.ec_arg4 = (uintptr_t)NULL;
@@ -428,6 +454,13 @@
 	return (efi_call(&ec));
 }
 
+int
+efi_reset_system(void)
+{
+
+	return (_efi_reset_system(EFI_RESET_WARM));
+}
+
 static int
 efi_set_time_locked(struct efi_tm *tm)
 {
Index: sys/dev/ipmi/ipmi.c
===================================================================
--- sys/dev/ipmi/ipmi.c
+++ sys/dev/ipmi/ipmi.c
@@ -938,14 +938,14 @@
 	} else if (!on)
 		(void)ipmi_set_watchdog(sc, 0);
 	/*
-	 * Power cycle the system off using IPMI. We use last - 1 since we don't
+	 * Power cycle the system off using IPMI. We use last - 2 since we don't
 	 * handle all the other kinds of reboots. We'll let others handle them.
 	 * We only try to do this if the BMC supports the Chassis device.
 	 */
 	if (sc->ipmi_dev_support & IPMI_ADS_CHASSIS) {
 		device_printf(dev, "Establishing power cycle handler\n");
 		sc->ipmi_power_cycle_tag = EVENTHANDLER_REGISTER(shutdown_final,
-		    ipmi_power_cycle, sc, SHUTDOWN_PRI_LAST - 1);
+		    ipmi_power_cycle, sc, SHUTDOWN_PRI_LAST - 2);
 	}
 }
 
Index: sys/sys/efi.h
===================================================================
--- sys/sys/efi.h
+++ sys/sys/efi.h
@@ -43,7 +43,8 @@
 
 enum efi_reset {
 	EFI_RESET_COLD,
-	EFI_RESET_WARM
+	EFI_RESET_WARM,
+	EFI_RESET_SHUTDOWN,
 };
 
 typedef uint16_t	efi_char;