diff --git a/photon/libc/include/time.h b/photon/libc/include/time.h
index e20d30c..53d67fc 100644
--- a/photon/libc/include/time.h
+++ b/photon/libc/include/time.h
@@ -6,7 +6,9 @@
 #include <sys/time.h>
 #include <sys/_time.h>
 
-#define CLOCKS_PER_SEC __SYS_CLOCKS_PER_SEC
+#define CLOCKS_PER_SEC  __SYS_CLOCKS_PER_SEC
+#define CLOCK_REALTIME  __SYS_CLOCK_REALTIME
+#define CLOCK_MONOTONIC __SYS_CLOCK_MONOTONIC
 
 struct timespec {
     time_t tv_sec;
@@ -35,4 +37,8 @@ extern size_t strftime(char *str, size_t max, const char *format, const struct t
 
 extern void tzset(void);
 
+extern int clock_getres(clockid_t clk_id, struct timespec *res);
+extern int clock_gettime(clockid_t clk_id, struct timespec *tp);
+extern int clock_settime(clockid_t clk_id, const struct timespec *tp);
+
 #endif
diff --git a/photon/libc/sys/horizon/sys/_time.h b/photon/libc/sys/horizon/sys/_time.h
index 58f9643..2cfb74c 100644
--- a/photon/libc/sys/horizon/sys/_time.h
+++ b/photon/libc/sys/horizon/sys/_time.h
@@ -1,11 +1,20 @@
 #ifndef SYS_HORIZON___TIME_H_
 #define SYS_HORIZON___TIME_H_
 
-#define __SYS_CLOCKS_PER_SEC 1000000000
+#include <sys/types.h>
+#include <magenta/clock.h>
 
-#include <time.h>
+#define __SYS_CLOCKS_PER_SEC 1000000000
+#define __SYS_CLOCK_REALTIME  MX_CLOCK_REALTIME
+#define __SYS_CLOCK_MONOTONIC MX_CLOCK_MONOTONIC
+
+struct timespec;
 
 extern clock_t __sys_clock(void);
 extern time_t __sys_time(void);
 
+extern int __sys_clock_getres(clockid_t clk_id, struct timespec *res);
+extern int __sys_clock_gettime(clockid_t clk_id, struct timespec *tp);
+extern int __sys_clock_settime(clockid_t clk_id, const struct timespec *tp);
+
 #endif
diff --git a/photon/libc/sys/horizon/time.c b/photon/libc/sys/horizon/time.c
index 984b367..6705b2e 100644
--- a/photon/libc/sys/horizon/time.c
+++ b/photon/libc/sys/horizon/time.c
@@ -1,4 +1,5 @@
 #include <magenta/types.h>
+#include <magenta/errors.h>
 #include <magenta/clock.h>
 #include <time.h>
 
@@ -17,3 +18,48 @@ time_t __sys_time(void)
 
     return v.sec;
 }
+
+int __sys_clock_getres(clockid_t clk_id, struct timespec *res)
+{
+    mx_time_val_t v;
+    mx_status_t s = mx_clock_get_resolution(clk_id, &v);
+
+    if (s != MX_OK) {
+        /* TODO set errno */
+        return -1;
+    }
+
+    res->tv_sec = v.sec;
+    res->tv_nsec = v.nsec;
+
+    return 0;
+}
+
+int __sys_clock_gettime(clockid_t clk_id, struct timespec *tp)
+{
+    mx_time_val_t v;
+    mx_status_t s = mx_clock_get_time(clk_id, &v);
+
+    if (s != MX_OK) {
+        /* TODO set errno */
+        return -1;
+    }
+
+    tp->tv_sec = v.sec;
+    tp->tv_nsec = v.nsec;
+
+    return 0;
+}
+
+int __sys_clock_settime(clockid_t clk_id, const struct timespec *tp)
+{
+    mx_time_val_t v = { .sec = tp->tv_sec, .nsec = tp->tv_nsec };
+    mx_status_t s = mx_clock_set_time(clk_id, &v);
+
+    if (s != MX_OK) {
+        /* TODO set errno */
+        return -1;
+    }
+
+    return 0;
+}
diff --git a/photon/libc/time/clock.c b/photon/libc/time/clock.c
index 65cb9e6..eb4b6ab 100644
--- a/photon/libc/time/clock.c
+++ b/photon/libc/time/clock.c
@@ -5,3 +5,18 @@ clock_t clock(void)
 {
     return __sys_clock();
 }
+
+int clock_getres(clockid_t clk_id, struct timespec *res)
+{
+    return __sys_clock_getres(clk_id, res);
+}
+
+int clock_gettime(clockid_t clk_id, struct timespec *tp)
+{
+    return __sys_clock_gettime(clk_id, tp);
+}
+
+int clock_settime(clockid_t clk_id, const struct timespec *tp)
+{
+    return __sys_clock_settime(clk_id, tp);
+}