Index: sys/x86/x86/tsc.c
===================================================================
--- sys/x86/x86/tsc.c	(revision 223102)
+++ sys/x86/x86/tsc.c	(working copy)
@@ -579,6 +579,9 @@ tsc_get_timecount(struct timecounter *tc __unused)
 static u_int
 tsc_get_timecount_low(struct timecounter *tc)
 {
+	uint32_t low, high;
 
-	return (rdtsc() >> (int)(intptr_t)tc->tc_priv);
+	__asm __volatile("rdtsc; shrd %2,%1,%0"
+	: "=a" (low), "=d" (high) : "Ic" ((uint8_t)(intptr_t)tc->tc_priv));
+	return (low);
 }