diff --git a/libc/bionic/sysconf.cpp b/libc/bionic/sysconf.cpp
index 7325dbd..d45cb38 100644
--- a/libc/bionic/sysconf.cpp
+++ b/libc/bionic/sysconf.cpp
@@ -148,7 +148,7 @@
     case _SC_THREAD_PRIO_INHERIT: return _POSIX_THREAD_PRIO_INHERIT;
     case _SC_THREAD_PRIO_PROTECT: return _POSIX_THREAD_PRIO_PROTECT;
     case _SC_THREAD_SAFE_FUNCTIONS:  return _POSIX_THREAD_SAFE_FUNCTIONS;
-    case _SC_MONOTONIC_CLOCK:   return _POSIX_VERSION;
+    case _SC_MONOTONIC_CLOCK:   return _POSIX_MONOTONIC_CLOCK;
 
     case _SC_2_PBS:             return -1;     // Obsolescent in POSIX.1-2008.
     case _SC_2_PBS_ACCOUNTING:  return -1;     // Obsolescent in POSIX.1-2008.
@@ -159,7 +159,7 @@
     case _SC_ADVISORY_INFO:     return _POSIX_ADVISORY_INFO;
     case _SC_BARRIERS:          return _POSIX_BARRIERS;
     case _SC_CLOCK_SELECTION:   return _POSIX_CLOCK_SELECTION;
-    case _SC_CPUTIME:           return _POSIX_VERSION;
+    case _SC_CPUTIME:           return _POSIX_CPUTIME;
 
     case _SC_HOST_NAME_MAX:     return _POSIX_HOST_NAME_MAX;    // Minimum requirement.
     case _SC_IPV6:              return _POSIX_IPV6;
@@ -172,7 +172,7 @@
     case _SC_SPORADIC_SERVER:   return _POSIX_SPORADIC_SERVER;
     case _SC_SS_REPL_MAX:       return -1;
     case _SC_SYMLOOP_MAX:       return _POSIX_SYMLOOP_MAX;      // Minimum requirement.
-    case _SC_THREAD_CPUTIME:    return _POSIX_VERSION;
+    case _SC_THREAD_CPUTIME:    return _POSIX_THREAD_CPUTIME;
 
     case _SC_THREAD_PROCESS_SHARED: return _POSIX_THREAD_PROCESS_SHARED;
     case _SC_THREAD_ROBUST_PRIO_INHERIT:  return _POSIX_THREAD_ROBUST_PRIO_INHERIT;
diff --git a/libc/include/bits/posix_limits.h b/libc/include/bits/posix_limits.h
index cfc46f5..f8db024 100644
--- a/libc/include/bits/posix_limits.h
+++ b/libc/include/bits/posix_limits.h
@@ -31,7 +31,11 @@
 
 #include <sys/cdefs.h>
 
-#define __BIONIC_POSIX_FEATURE_SINCE(level) (((__ANDROID_API__) >= level) ? 200809L : -1)
+#define _POSIX_VERSION 200809L
+#define _POSIX2_VERSION _POSIX_VERSION
+#define _XOPEN_VERSION 700
+
+#define __BIONIC_POSIX_FEATURE_SINCE(level) (((__ANDROID_API__) >= level) ? _POSIX_VERSION : -1)
 
 /* Any constant values here other than -1 or 200809L are explicitly specified by POSIX.1-2008. */
 /* Keep this list sorted by name. */
@@ -43,8 +47,8 @@
 #define _POSIX_BARRIERS __BIONIC_POSIX_FEATURE_SINCE(24)
 #define _POSIX_CHILD_MAX            25
 #define _POSIX_CHOWN_RESTRICTED     1  /* yes, chown requires appropriate privileges */
-#define _POSIX_CLOCK_SELECTION      200809L
-#define _POSIX_CPUTIME              0  /* Use sysconf to detect support at runtime. */
+#define _POSIX_CLOCK_SELECTION __BIONIC_POSIX_FEATURE_SINCE(21) /* clock_nanosleep/pthread_condattr_getclock/pthread_condattr_setclock. */
+#define _POSIX_CPUTIME _POSIX_VERSION /* CLOCK_PROCESS_CPUTIME_ID. */
 #define _POSIX_DELAYTIMER_MAX       32
 #define _POSIX_FSYNC 200809L
 #define _POSIX_HOST_NAME_MAX        255
@@ -59,7 +63,7 @@
 #define _POSIX_MEMLOCK_RANGE        200809L /* mlock. */
 #define _POSIX_MEMORY_PROTECTION    200809L
 #define _POSIX_MESSAGE_PASSING      -1  /* not implemented */
-#define _POSIX_MONOTONIC_CLOCK      0  /* the monotonic clock may be available; ask sysconf */
+#define _POSIX_MONOTONIC_CLOCK _POSIX_VERSION /* CLOCK_MONOTONIC. */
 #define _POSIX_MQ_OPEN_MAX          8
 #define _POSIX_MQ_PRIO_MAX          32
 #define _POSIX_NAME_MAX             14
@@ -93,7 +97,7 @@
 #define _POSIX_THREADS              200809L  /* we support threads */
 #define _POSIX_THREAD_ATTR_STACKADDR  200809L
 #define _POSIX_THREAD_ATTR_STACKSIZE  200809L
-#define _POSIX_THREAD_CPUTIME       0  /* Use sysconf to detect support at runtime. */
+#define _POSIX_THREAD_CPUTIME _POSIX_VERSION /* CLOCK_THREAD_CPUTIME_ID. */
 #define _POSIX_THREAD_DESTRUCTOR_ITERATIONS 4
 #define _POSIX_THREAD_KEYS_MAX      128
 #define _POSIX_THREAD_PRIORITY_SCHEDULING 200809L
diff --git a/libc/include/limits.h b/libc/include/limits.h
index 51f4fad..4384f6f 100644
--- a/libc/include/limits.h
+++ b/libc/include/limits.h
@@ -140,10 +140,6 @@
 #define LOGIN_NAME_MAX 256
 #define TTY_NAME_MAX 32
 
-#define _POSIX_VERSION 200809L
-#define _POSIX2_VERSION _POSIX_VERSION
-#define _XOPEN_VERSION 700       /* by Posix definition */
-
 /* >= _POSIX_THREAD_DESTRUCTOR_ITERATIONS */
 #define PTHREAD_DESTRUCTOR_ITERATIONS 4
 /* >= _POSIX_THREAD_KEYS_MAX */
diff --git a/tests/time_test.cpp b/tests/time_test.cpp
index 4e3fa83..d553ff5 100644
--- a/tests/time_test.cpp
+++ b/tests/time_test.cpp
@@ -574,6 +574,31 @@
   ASSERT_LT(ts2.tv_nsec, 1000000);
 }
 
+TEST(time, clock_gettime_CLOCK_REALTIME) {
+  timespec ts;
+  ASSERT_EQ(0, clock_gettime(CLOCK_REALTIME, &ts));
+}
+
+TEST(time, clock_gettime_CLOCK_MONOTONIC) {
+  timespec ts;
+  ASSERT_EQ(0, clock_gettime(CLOCK_MONOTONIC, &ts));
+}
+
+TEST(time, clock_gettime_CLOCK_PROCESS_CPUTIME_ID) {
+  timespec ts;
+  ASSERT_EQ(0, clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &ts));
+}
+
+TEST(time, clock_gettime_CLOCK_THREAD_CPUTIME_ID) {
+  timespec ts;
+  ASSERT_EQ(0, clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ts));
+}
+
+TEST(time, clock_gettime_CLOCK_BOOTTIME) {
+  timespec ts;
+  ASSERT_EQ(0, clock_gettime(CLOCK_BOOTTIME, &ts));
+}
+
 TEST(time, clock) {
   // clock(3) is hard to test, but a 1s sleep should cost less than 1ms.
   clock_t t0 = clock();
diff --git a/tests/unistd_test.cpp b/tests/unistd_test.cpp
index cd51e1b..2917130 100644
--- a/tests/unistd_test.cpp
+++ b/tests/unistd_test.cpp
@@ -701,7 +701,7 @@
   EXPECT_GT(_POSIX_CHILD_MAX, 0);
   EXPECT_NE(_POSIX_CHOWN_RESTRICTED, -1);
   EXPECT_EQ(_POSIX_VERSION, _POSIX_CLOCK_SELECTION);
-  EXPECT_EQ(0, _POSIX_CPUTIME);             // Use sysconf to detect support at runtime.
+  EXPECT_EQ(_POSIX_VERSION, _POSIX_CPUTIME);
   EXPECT_GT(_POSIX_DELAYTIMER_MAX, 0);
   EXPECT_EQ(_POSIX_VERSION, _POSIX_FSYNC);
   EXPECT_GT(_POSIX_HOST_NAME_MAX, 0);
@@ -715,7 +715,7 @@
   EXPECT_EQ(_POSIX_VERSION, _POSIX_MEMLOCK);
   EXPECT_EQ(_POSIX_VERSION, _POSIX_MEMLOCK_RANGE);
   EXPECT_EQ(_POSIX_VERSION, _POSIX_MEMORY_PROTECTION);
-  EXPECT_EQ(0, _POSIX_MONOTONIC_CLOCK);
+  EXPECT_EQ(_POSIX_VERSION, _POSIX_MONOTONIC_CLOCK);
   EXPECT_GT(_POSIX_MQ_OPEN_MAX, 0);
   EXPECT_GT(_POSIX_MQ_PRIO_MAX, 0);
   EXPECT_GT(_POSIX_NAME_MAX, 0);
@@ -745,7 +745,7 @@
   EXPECT_EQ(_POSIX_VERSION, _POSIX_THREADS);
   EXPECT_EQ(_POSIX_VERSION, _POSIX_THREAD_ATTR_STACKADDR);
   EXPECT_EQ(_POSIX_VERSION, _POSIX_THREAD_ATTR_STACKSIZE);
-  EXPECT_EQ(0, _POSIX_THREAD_CPUTIME);       // Use sysconf to detect support at runtime.
+  EXPECT_EQ(_POSIX_VERSION, _POSIX_THREAD_CPUTIME);
   EXPECT_GT(_POSIX_THREAD_DESTRUCTOR_ITERATIONS, 0);
   EXPECT_EQ(_POSIX_THREAD_KEYS_MAX, 128);
   EXPECT_EQ(_POSIX_VERSION, _POSIX_THREAD_PRIORITY_SCHEDULING);