diff --git a/sys/dev/hwpmc/hwpmc_amd.c b/sys/dev/hwpmc/hwpmc_amd.c
--- a/sys/dev/hwpmc/hwpmc_amd.c
+++ b/sys/dev/hwpmc/hwpmc_amd.c
@@ -431,9 +431,18 @@
 	tmp = rdmsr(pd->pm_perfctr); /* RDMSR serializes */
 	PMCDBG2(MDP,REA,2,"amd-read (pre-munge) id=%d -> %jd", ri, tmp);
 	if (PMC_IS_SAMPLING_MODE(mode)) {
-		/* Sign extend 48 bit value to 64 bits. */
-		tmp = (pmc_value_t) (((int64_t) tmp << 16) >> 16);
-		tmp = AMD_PERFCTR_VALUE_TO_RELOAD_COUNT(tmp);
+		/*
+		 * Clamp value to 0 if the counter just overflowed,
+		 * otherwise the returned reload count would wrap to a
+		 * huge value.
+		 */
+		if ((tmp & (1ULL << 47)) == 0)
+			tmp = 0;
+		else {
+			/* Sign extend 48 bit value to 64 bits. */
+			tmp = (pmc_value_t) ((int64_t)(tmp << 16) >> 16);
+			tmp = AMD_PERFCTR_VALUE_TO_RELOAD_COUNT(tmp);
+		}
 	}
 	*v = tmp;
 
diff --git a/sys/dev/hwpmc/hwpmc_arm64.c b/sys/dev/hwpmc/hwpmc_arm64.c
--- a/sys/dev/hwpmc/hwpmc_arm64.c
+++ b/sys/dev/hwpmc/hwpmc_arm64.c
@@ -218,8 +218,7 @@
 	if ((READ_SPECIALREG(pmovsclr_el0) & reg) != 0) {
 		/* Clear Overflow Flag */
 		WRITE_SPECIALREG(pmovsclr_el0, reg);
-		if (!PMC_IS_SAMPLING_MODE(PMC_TO_MODE(pm)))
-			pm->pm_pcpu_state[cpu].pps_overflowcnt++;
+		pm->pm_pcpu_state[cpu].pps_overflowcnt++;
 
 		/* Reread counter in case we raced. */
 		tmp = arm64_pmcn_read(ri);
@@ -228,10 +227,18 @@
 	intr_restore(s);
 
 	PMCDBG2(MDP, REA, 2, "arm64-read id=%d -> %jd", ri, tmp);
-	if (PMC_IS_SAMPLING_MODE(PMC_TO_MODE(pm)))
-		*v = ARMV8_PERFCTR_VALUE_TO_RELOAD_COUNT(tmp);
-	else
-		*v = tmp;
+	if (PMC_IS_SAMPLING_MODE(PMC_TO_MODE(pm))) {
+		/*
+		 * Clamp value to 0 if the counter just overflowed,
+		 * otherwise the returned reload count would wrap to a
+		 * huge value.
+		 */
+		if ((tmp & (1ull << 63)) == 0)
+			tmp = 0;
+		else
+			tmp = ARMV8_PERFCTR_VALUE_TO_RELOAD_COUNT(tmp);
+	}
+	*v = tmp;
 
 	return (0);
 }
@@ -379,10 +386,10 @@
 
 		retval = 1; /* Found an interrupting PMC. */
 
-		if (!PMC_IS_SAMPLING_MODE(PMC_TO_MODE(pm))) {
-			pm->pm_pcpu_state[cpu].pps_overflowcnt += 1;
+		pm->pm_pcpu_state[cpu].pps_overflowcnt += 1;
+
+		if (!PMC_IS_SAMPLING_MODE(PMC_TO_MODE(pm)))
 			continue;
-		}
 
 		if (pm->pm_state != PMC_STATE_RUNNING)
 			continue;
diff --git a/sys/dev/hwpmc/hwpmc_armv7.c b/sys/dev/hwpmc/hwpmc_armv7.c
--- a/sys/dev/hwpmc/hwpmc_armv7.c
+++ b/sys/dev/hwpmc/hwpmc_armv7.c
@@ -189,8 +189,7 @@
 	if ((cp15_pmovsr_get() & reg) != 0) {
 		/* Clear Overflow Flag */
 		cp15_pmovsr_set(reg);
-		if (!PMC_IS_SAMPLING_MODE(PMC_TO_MODE(pm)))
-			pm->pm_pcpu_state[cpu].pps_overflowcnt++;
+		pm->pm_pcpu_state[cpu].pps_overflowcnt++;
 
 		/* Reread counter in case we raced. */
 		tmp = armv7_pmcn_read(ri, pm->pm_md.pm_armv7.pm_armv7_evsel);
@@ -199,10 +198,18 @@
 	intr_restore(s);
 
 	PMCDBG2(MDP, REA, 2, "armv7-read id=%d -> %jd", ri, tmp);
-	if (PMC_IS_SAMPLING_MODE(PMC_TO_MODE(pm)))
-		*v = ARMV7_PERFCTR_VALUE_TO_RELOAD_COUNT(tmp);
-	else
-		*v = tmp;
+	if (PMC_IS_SAMPLING_MODE(PMC_TO_MODE(pm))) {
+		/*
+		 * Clamp value to 0 if the counter just overflowed,
+		 * otherwise the returned reload count would wrap to a
+		 * huge value.
+		 */
+		if ((tmp & (1ull << 63)) == 0)
+			tmp = 0;
+		else
+			tmp = ARMV7_PERFCTR_VALUE_TO_RELOAD_COUNT(tmp);
+	}
+	*v = tmp;
 
 	return 0;
 }
@@ -360,10 +367,11 @@
 
 		retval = 1; /* Found an interrupting PMC. */
 
-		if (!PMC_IS_SAMPLING_MODE(PMC_TO_MODE(pm))) {
-			pm->pm_pcpu_state[cpu].pps_overflowcnt += 1;
+		pm->pm_pcpu_state[cpu].pps_overflowcnt += 1;
+
+		if (!PMC_IS_SAMPLING_MODE(PMC_TO_MODE(pm)))
 			continue;
-		}
+
 		if (pm->pm_state != PMC_STATE_RUNNING)
 			continue;
 
diff --git a/sys/dev/hwpmc/hwpmc_uncore.c b/sys/dev/hwpmc/hwpmc_uncore.c
--- a/sys/dev/hwpmc/hwpmc_uncore.c
+++ b/sys/dev/hwpmc/hwpmc_uncore.c
@@ -175,6 +175,10 @@
 static pmc_value_t
 ucf_perfctr_value_to_reload_count(pmc_value_t v)
 {
+
+	/* If the PMC has overflowed, return a reload count of zero. */
+	if ((v & (1ULL << (uncore_ucf_width - 1))) == 0)
+		return (0);
 	v &= (1ULL << uncore_ucf_width) - 1;
 	return (1ULL << uncore_ucf_width) - v;
 }