diff --git a/ChangeLog b/ChangeLog
index 641e921d96..fa43db1d04 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue Sep  3 12:09:08 2013  Tanaka Akira  <akr@fsij.org>
+
+	* process.c (rb_clock_gettime): Support times() based monotonic clock.
+	  (rb_clock_getres): Ditto.
+
 Tue Sep  3 12:03:02 2013  Tanaka Akira  <akr@fsij.org>
 
 	* bignum.c (str2big_scan_digits): Extracted from rb_cstr_to_inum.
diff --git a/process.c b/process.c
index 07649f1b0c..e2bd716d85 100644
--- a/process.c
+++ b/process.c
@@ -6926,6 +6926,17 @@ get_mach_timebase_info(void)
  *  [:MACH_ABSOLUTE_TIME_BASED_CLOCK_MONOTONIC]
  *    Use mach_absolute_time(), available on Darwin.
  *    The resolution is CPU dependent.
+ *  [:TIMES_BASED_CLOCK_MONOTONIC]
+ *    Use the result value of times() defined by POSIX.
+ *    POSIX defines it as "times() shall return the elapsed real time, in clock ticks, since an arbitrary point in the past (for example, system start-up time)".
+ *    For example, GNU/Linux returns a value based on jiffies and it is monotonic.
+ *    However, 4.4BSD uses gettimeofday() and it is not monotonic.
+ *    (FreeBSD uses clock_gettime(CLOCK_MONOTONIC) instead, though.)
+ *    The resolution is the clock tick.
+ *    "getconf CLK_TCK" command shows the clock ticks per second.
+ *    (The clock ticks per second is defined by HZ macro in older systems.)
+ *    If it is 100 and clock_t is 32 bits integer type, the resolution is 10 milli second and
+ *    cannot represent over 497 days.
  *
  *  Emulations for +CLOCK_PROCESS_CPUTIME_ID+:
  *  [:GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID]
@@ -7022,6 +7033,24 @@ rb_clock_gettime(int argc, VALUE *argv)
             goto success;
         }
 
+#ifdef HAVE_TIMES
+#define RUBY_TIMES_BASED_CLOCK_MONOTONIC \
+        ID2SYM(rb_intern("TIMES_BASED_CLOCK_MONOTONIC"))
+        if (clk_id == RUBY_TIMES_BASED_CLOCK_MONOTONIC) {
+            struct tms buf;
+            clock_t c;
+            unsigned_clock_t uc;
+            c = times(&buf);
+            if (c ==  (clock_t)-1)
+                rb_sys_fail("times");
+            uc = (unsigned_clock_t)c;
+            tt.count = (int32_t)(uc % 1000000000);
+            tt.giga_count = (uc / 1000000000);
+            denominators[num_denominators++] = get_clk_tck();
+            goto success;
+        }
+#endif
+
 #ifdef RUSAGE_SELF
 #define RUBY_GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID \
         ID2SYM(rb_intern("GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID"))
@@ -7186,6 +7215,15 @@ rb_clock_getres(int argc, VALUE *argv)
         }
 #endif
 
+#ifdef RUBY_TIMES_BASED_CLOCK_MONOTONIC
+        if (clk_id == RUBY_TIMES_BASED_CLOCK_MONOTONIC) {
+            tt.count = 1;
+            tt.giga_count = 0;
+            denominators[num_denominators++] = get_clk_tck();
+            goto success;
+        }
+#endif
+
 #ifdef RUBY_GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID
         if (clk_id == RUBY_GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID) {
             tt.giga_count = 0;
diff --git a/test/ruby/test_process.rb b/test/ruby/test_process.rb
index 8b15679671..fa69d4b916 100644
--- a/test/ruby/test_process.rb
+++ b/test/ruby/test_process.rb
@@ -1693,6 +1693,16 @@ EOS
     assert_kind_of(Float, t, "Process.clock_gettime(:#{n})")
   end
 
+  def test_clock_gettime_TIMES_BASED_CLOCK_MONOTONIC
+    n = :TIMES_BASED_CLOCK_MONOTONIC
+    begin
+      t = Process.clock_gettime(n)
+    rescue Errno::EINVAL
+      return
+    end
+    assert_kind_of(Float, t, "Process.clock_gettime(:#{n})")
+  end
+
   def test_clock_gettime_GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID
     n = :GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID
     begin
@@ -1761,6 +1771,18 @@ EOS
     assert_equal(1000000000, Process.clock_getres(n, :nanosecond))
   end
 
+  def test_clock_getres_TIMES_BASED_CLOCK_MONOTONIC
+    n = :TIMES_BASED_CLOCK_MONOTONIC
+    begin
+      t = Process.clock_getres(n)
+    rescue Errno::EINVAL
+      return
+    end
+    assert_kind_of(Float, t, "Process.clock_getres(:#{n})")
+    f = Process.clock_getres(n, :hertz)
+    assert_equal(0, f - f.floor)
+  end
+
   def test_clock_getres_GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID
     n = :GETRUSAGE_BASED_CLOCK_PROCESS_CPUTIME_ID
     begin