diff --git a/sys/x86/isa/clock.c b/sys/x86/isa/clock.c
index 8fa642295611..a0bf60159e78 100644
--- a/sys/x86/isa/clock.c
+++ b/sys/x86/isa/clock.c
@@ -411,7 +411,6 @@ startrtclock(void)
 void
 cpu_initclocks(void)
 {
-#ifdef EARLY_AP_STARTUP
 	struct thread *td;
 	int i;
 
@@ -434,13 +433,6 @@ cpu_initclocks(void)
 	if (sched_is_bound(td))
 		sched_unbind(td);
 	thread_unlock(td);
-#else
-	tsc_calibrate();
-#ifdef DEV_APIC
-	lapic_calibrate_timer();
-#endif
-	cpu_initclocks_bsp();
-#endif
 }
 
 static int
diff --git a/sys/x86/x86/intr_machdep.c b/sys/x86/x86/intr_machdep.c
index b43fa790d264..458a0cb396bb 100644
--- a/sys/x86/x86/intr_machdep.c
+++ b/sys/x86/x86/intr_machdep.c
@@ -90,7 +90,7 @@ static TAILQ_HEAD(pics_head, pic) pics;
 u_int num_io_irqs;
 
 #if defined(SMP) && !defined(EARLY_AP_STARTUP)
-static int assign_cpu;
+#error EARLY_AP_STARTUP required on x86
 #endif
 
 #define	INTRNAME_LEN	(MAXCOMLEN + 1)
@@ -399,18 +399,10 @@ intr_assign_cpu(void *arg, int cpu)
 	struct intsrc *isrc;
 	int error;
 
-#ifdef EARLY_AP_STARTUP
 	MPASS(mp_ncpus == 1 || smp_started);
 
 	/* Nothing to do if there is only a single CPU. */
 	if (mp_ncpus > 1 && cpu != NOCPU) {
-#else
-	/*
-	 * Don't do anything during early boot.  We will pick up the
-	 * assignment once the APs are started.
-	 */
-	if (assign_cpu && cpu != NOCPU) {
-#endif
 		isrc = arg;
 		sx_xlock(&intrsrc_lock);
 		error = isrc->is_pic->pic_assign_cpu(isrc, cpu_apic_ids[cpu]);
@@ -620,15 +612,9 @@ intr_next_cpu(int domain)
 {
 	u_int apic_id;
 
-#ifdef EARLY_AP_STARTUP
 	MPASS(mp_ncpus == 1 || smp_started);
 	if (mp_ncpus == 1)
 		return (PCPU_GET(apic_id));
-#else
-	/* Leave all interrupts on the BSP during boot. */
-	if (!assign_cpu)
-		return (PCPU_GET(apic_id));
-#endif
 
 	if (intr_no_domain)
 		domain = 0;
@@ -662,7 +648,6 @@ intr_add_cpu(u_int cpu)
 	CPU_SET(cpu, &intr_cpus);
 }
 
-#ifdef EARLY_AP_STARTUP
 static void
 intr_smp_startup(void *arg __unused)
 {
@@ -673,52 +658,6 @@ intr_smp_startup(void *arg __unused)
 SYSINIT(intr_smp_startup, SI_SUB_SMP, SI_ORDER_SECOND, intr_smp_startup,
     NULL);
 
-#else
-/*
- * Distribute all the interrupt sources among the available CPUs once the
- * AP's have been launched.
- */
-static void
-intr_shuffle_irqs(void *arg __unused)
-{
-	struct intsrc *isrc;
-	u_int cpu, i;
-
-	intr_init_cpus();
-	/* Don't bother on UP. */
-	if (mp_ncpus == 1)
-		return;
-
-	/* Round-robin assign a CPU to each enabled source. */
-	sx_xlock(&intrsrc_lock);
-	assign_cpu = 1;
-	for (i = 0; i < num_io_irqs; i++) {
-		isrc = interrupt_sources[i];
-		if (isrc != NULL && isrc->is_handlers > 0) {
-			/*
-			 * If this event is already bound to a CPU,
-			 * then assign the source to that CPU instead
-			 * of picking one via round-robin.  Note that
-			 * this is careful to only advance the
-			 * round-robin if the CPU assignment succeeds.
-			 */
-			cpu = isrc->is_event->ie_cpu;
-			if (cpu == NOCPU)
-				cpu = current_cpu[isrc->is_domain];
-			if (isrc->is_pic->pic_assign_cpu(isrc,
-			    cpu_apic_ids[cpu]) == 0) {
-				isrc->is_cpu = cpu;
-				if (isrc->is_event->ie_cpu == NOCPU)
-					intr_next_cpu(isrc->is_domain);
-			}
-		}
-	}
-	sx_xunlock(&intrsrc_lock);
-}
-SYSINIT(intr_shuffle_irqs, SI_SUB_SMP, SI_ORDER_SECOND, intr_shuffle_irqs,
-    NULL);
-#endif
-
 /*
  * TODO: Export this information in a non-MD fashion, integrate with vmstat -i.
  */
diff --git a/sys/x86/x86/local_apic.c b/sys/x86/x86/local_apic.c
index b382368cc626..43fe4625cd08 100644
--- a/sys/x86/x86/local_apic.c
+++ b/sys/x86/x86/local_apic.c
@@ -876,22 +876,8 @@ lapic_enable_pmc(void)
 
 	lvts[APIC_LVT_PMC].lvt_masked = 0;
 
-#ifdef EARLY_AP_STARTUP
 	MPASS(mp_ncpus == 1 || smp_started);
 	smp_rendezvous(NULL, lapic_update_pmc, NULL, NULL);
-#else
-#ifdef SMP
-	/*
-	 * If hwpmc was loaded at boot time then the APs may not be
-	 * started yet.  In that case, don't forward the request to
-	 * them as they will program the lvt when they start.
-	 */
-	if (smp_started)
-		smp_rendezvous(NULL, lapic_update_pmc, NULL, NULL);
-	else
-#endif
-		lapic_update_pmc(NULL);
-#endif
 	return (1);
 #else
 	return (0);
diff --git a/sys/x86/x86/mca.c b/sys/x86/x86/mca.c
index dca6b935e4a3..b293fcedbd84 100644
--- a/sys/x86/x86/mca.c
+++ b/sys/x86/x86/mca.c
@@ -1077,11 +1077,7 @@ mca_startup(void *dummy)
 	taskqueue_enqueue_timeout_sbt(mca_tq, &mca_scan_task,
 	    mca_ticks * SBT_1S, 0, C_PREL(1));
 }
-#ifdef EARLY_AP_STARTUP
 SYSINIT(mca_startup, SI_SUB_KICK_SCHEDULER, SI_ORDER_ANY, mca_startup, NULL);
-#else
-SYSINIT(mca_startup, SI_SUB_SMP, SI_ORDER_ANY, mca_startup, NULL);
-#endif
 
 #ifdef DEV_APIC
 static void
diff --git a/sys/x86/x86/mp_x86.c b/sys/x86/x86/mp_x86.c
index ddcb54b63d88..11b11471d736 100644
--- a/sys/x86/x86/mp_x86.c
+++ b/sys/x86/x86/mp_x86.c
@@ -1133,11 +1133,6 @@ init_secondary_tail(void)
 	while (atomic_load_acq_int(&smp_started) == 0)
 		ia32_pause();
 
-#ifndef EARLY_AP_STARTUP
-	/* Start per-CPU event timers. */
-	cpu_initclocks_ap();
-#endif
-
 	kcsan_cpu_init(cpuid);
 
 	sched_ap_entry();