diff --git a/hw/pc_piix.c b/hw/pc_piix.c
index 62cdf71daa..9a22a8afc8 100644
--- a/hw/pc_piix.c
+++ b/hw/pc_piix.c
@@ -179,7 +179,11 @@ static void pc_init1(ram_addr_t ram_size,
     if (pci_enabled && acpi_enabled) {
         i2c_bus *smbus;
 
-        cmos_s3 = qemu_allocate_irqs(pc_cmos_set_s3_resume, rtc_state, 1);
+        if (!xen_enabled()) {
+            cmos_s3 = qemu_allocate_irqs(pc_cmos_set_s3_resume, rtc_state, 1);
+        } else {
+            cmos_s3 = qemu_allocate_irqs(xen_cmos_set_s3_resume, rtc_state, 1);
+        }
         smi_irq = qemu_allocate_irqs(pc_acpi_smi_interrupt, first_cpu, 1);
         /* TODO: Populate SPD eeprom data.  */
         smbus = piix4_pm_init(pci_bus, piix3_devfn + 3, 0xb100,
diff --git a/hw/xen.h b/hw/xen.h
index 6245b38153..d435ca0ce5 100644
--- a/hw/xen.h
+++ b/hw/xen.h
@@ -43,6 +43,7 @@ static inline int xen_mapcache_enabled(void)
 int xen_pci_slot_get_pirq(PCIDevice *pci_dev, int irq_num);
 void xen_piix3_set_irq(void *opaque, int irq_num, int level);
 void xen_piix_pci_write_config_client(uint32_t address, uint32_t val, int len);
+void xen_cmos_set_s3_resume(void *opaque, int irq, int level);
 
 qemu_irq *xen_interrupt_controller_init(void);
 
diff --git a/xen-all.c b/xen-all.c
index 19c2fe1e0f..0eac202d4e 100644
--- a/xen-all.c
+++ b/xen-all.c
@@ -9,6 +9,7 @@
 #include <sys/mman.h>
 
 #include "hw/pci.h"
+#include "hw/pc.h"
 #include "hw/xen_common.h"
 #include "hw/xen_backend.h"
 
@@ -99,6 +100,14 @@ void xen_piix_pci_write_config_client(uint32_t address, uint32_t val, int len)
     }
 }
 
+void xen_cmos_set_s3_resume(void *opaque, int irq, int level)
+{
+    pc_cmos_set_s3_resume(opaque, irq, level);
+    if (level) {
+        xc_set_hvm_param(xen_xc, xen_domid, HVM_PARAM_ACPI_S_STATE, 3);
+    }
+}
+
 /* Xen Interrupt Controller */
 
 static void xen_set_irq(void *opaque, int irq, int level)
diff --git a/xen-stub.c b/xen-stub.c
index 8d2fa54b4b..a4f35a19fb 100644
--- a/xen-stub.c
+++ b/xen-stub.c
@@ -22,6 +22,10 @@ void xen_piix_pci_write_config_client(uint32_t address, uint32_t val, int len)
 {
 }
 
+void xen_cmos_set_s3_resume(void *opaque, int irq, int level)
+{
+}
+
 void xen_ram_alloc(ram_addr_t ram_addr, ram_addr_t size)
 {
 }