Index: head/sys/x86/x86/tsc.c
===================================================================
--- head/sys/x86/x86/tsc.c
+++ head/sys/x86/x86/tsc.c
@@ -134,7 +134,11 @@
 
 /*
  * Calculate TSC frequency using information from the CPUID leaf 0x15
- * 'Time Stamp Counter and Nominal Core Crystal Clock'.  It should be
+ * 'Time Stamp Counter and Nominal Core Crystal Clock'.  If leaf 0x15
+ * is not functional, as it is on Skylake/Kabylake, try 0x16 'Processor
+ * Frequency Information'.  Leaf 0x16 is described in the SDM as
+ * informational only, but if 0x15 did not work, and TSC calibration
+ * is disabled, it is the best we can get at all.  It should still be
  * an improvement over the parsing of the CPU model name in
  * tsc_freq_intel(), when available.
  */
@@ -146,10 +150,20 @@
 	if (cpu_high < 0x15)
 		return (false);
 	do_cpuid(0x15, regs);
-	if (regs[0] == 0 || regs[1] == 0 || regs[2] == 0)
+	if (regs[0] != 0 && regs[1] != 0 && regs[2] != 0) {
+		tsc_freq = (uint64_t)regs[2] * regs[1] / regs[0];
+		return (true);
+	}
+
+	if (cpu_high < 0x16)
 		return (false);
-	tsc_freq = (uint64_t)regs[2] * regs[1] / regs[0];
-	return (true);
+	do_cpuid(0x16, regs);
+	if (regs[0] != 0) {
+		tsc_freq = (uint64_t)regs[0] * 1000000;
+		return (true);
+	}
+
+	return (false);
 }
 
 static void