diff --git a/sys/kern/kern_clock.c b/sys/kern/kern_clock.c
--- a/sys/kern/kern_clock.c
+++ b/sys/kern/kern_clock.c
@@ -556,60 +556,39 @@
 }
 
 /*
- * Compute number of ticks in the specified amount of time.
+ * Compute number of ticks representing the specified amount of time.
+ * If the specified time is negative, a value of 1 is returned. This
+ * function returns a value from 1 up to and including INT_MAX.
  */
 int
 tvtohz(struct timeval *tv)
 {
-	unsigned long ticks;
-	long sec, usec;
+	int64_t retval;
+
+	/* range check tv_sec so the multiplication below doesn't overflow */
+	if (__predict_false(tv->tv_sec > INT_MAX))
+		return (INT_MAX);
+	else if (__predict_false(tv->tv_sec < 0))
+		return (1);
 
 	/*
-	 * If the number of usecs in the whole seconds part of the time
-	 * difference fits in a long, then the total number of usecs will
-	 * fit in an unsigned long.  Compute the total and convert it to
-	 * ticks, rounding up and adding 1 to allow for the current tick
-	 * to expire.  Rounding also depends on unsigned long arithmetic
-	 * to avoid overflow.
-	 *
-	 * Otherwise, if the number of ticks in the whole seconds part of
-	 * the time difference fits in a long, then convert the parts to
-	 * ticks separately and add, using similar rounding methods and
-	 * overflow avoidance.  This method would work in the previous
-	 * case but it is slightly slower and assumes that hz is integral.
-	 *
-	 * Otherwise, round the time difference down to the maximum
-	 * representable value.
-	 *
-	 * If ints have 32 bits, then the maximum value for any timeout in
-	 * 10ms ticks is 248 days.
+	 * Convert to ticks. The cast to 32-bit tells the compiler on
+	 * 32-bit platforms it can use a regular 32-bit multiplication
+	 * with 64-bit result as an optimization, instead of a full
+	 * 64-bit multiplication.
 	 */
-	sec = tv->tv_sec;
-	usec = tv->tv_usec;
-	if (usec < 0) {
-		sec--;
-		usec += 1000000;
-	}
-	if (sec < 0) {
-#ifdef DIAGNOSTIC
-		if (usec > 0) {
-			sec++;
-			usec -= 1000000;
-		}
-		printf("tvotohz: negative time difference %ld sec %ld usec\n",
-		       sec, usec);
-#endif
-		ticks = 1;
-	} else if (sec <= LONG_MAX / 1000000)
-		ticks = howmany(sec * 1000000 + (unsigned long)usec, tick) + 1;
-	else if (sec <= LONG_MAX / hz)
-		ticks = sec * hz
-			+ howmany((unsigned long)usec, tick) + 1;
-	else
-		ticks = LONG_MAX;
-	if (ticks > INT_MAX)
-		ticks = INT_MAX;
-	return ((int)ticks);
+	retval =
+	    (int64_t)(int32_t)tv->tv_sec * hz +
+	    (int64_t)(int32_t)tv->tv_usec * hz / 1000000;
+
+	/* range check */
+	if (__predict_false(retval > INT_MAX - 1))
+		return (INT_MAX);
+	else if (__predict_false(retval < 0))
+		return (1);
+
+	/* add one additional tick */
+	return ((int)retval + 1);
 }
 
 /*