Index: sys/x86/x86/mp_x86.c
===================================================================
--- sys/x86/x86/mp_x86.c
+++ sys/x86/x86/mp_x86.c
@@ -1397,8 +1397,10 @@
 cpustop_handler(void)
 {
 	u_int cpu;
+	int apic;
 
 	cpu = PCPU_GET(cpuid);
+	apic = PCPU_GET(apic_id);
 
 	savectx(&stoppcbs[cpu]);
 
@@ -1406,8 +1408,17 @@
 	CPU_SET_ATOMIC(cpu, &stopped_cpus);
 
 	/* Wait for restart */
-	while (!CPU_ISSET(cpu, &started_cpus))
-	    ia32_pause();
+	while (!CPU_ISSET(cpu, &started_cpus)) {
+		ia32_pause();
+
+		/*
+		 * Halt non-BSP CPUs on panic -- we're never going to need them
+		 * again, and might as well save power / release resources
+		 * (e.g., overprovisioned VM infrastructure).
+		 */
+		while (__predict_false(!IS_BSP() && panicstr != NULL))
+			halt();
+	}
 
 	cpustop_handler_post(cpu);
 }