diff --git a/libc/bionic/clock.cpp b/libc/bionic/clock.cpp
index 053e9e7..fda0708 100644
--- a/libc/bionic/clock.cpp
+++ b/libc/bionic/clock.cpp
@@ -26,9 +26,9 @@
  * SUCH DAMAGE.
  */
 
-#include <time.h>
-#include <sys/sysconf.h>
 #include <sys/times.h>
+#include <time.h>
+#include <unistd.h>
 
 #include "private/bionic_constants.h"
 
diff --git a/libc/bionic/sysconf.cpp b/libc/bionic/sysconf.cpp
index cff6288..7be0ab7 100644
--- a/libc/bionic/sysconf.cpp
+++ b/libc/bionic/sysconf.cpp
@@ -34,7 +34,6 @@
 #include <stdio.h>  // For FOPEN_MAX.
 #include <sys/auxv.h>
 #include <sys/resource.h>
-#include <sys/sysconf.h>
 #include <sys/sysinfo.h>
 #include <time.h>
 #include <unistd.h>
diff --git a/libc/include/bits/sysconf.h b/libc/include/bits/sysconf.h
new file mode 100644
index 0000000..2cbbb11
--- /dev/null
+++ b/libc/include/bits/sysconf.h
@@ -0,0 +1,196 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef _BITS_SYSCONF_H_
+#define _BITS_SYSCONF_H_
+
+#include <sys/cdefs.h>
+
+/* as listed by Posix sysconf() description */
+/* most of these will return -1 and ENOSYS  */
+
+#define _SC_ARG_MAX             0x0000
+#define _SC_BC_BASE_MAX         0x0001
+#define _SC_BC_DIM_MAX          0x0002
+#define _SC_BC_SCALE_MAX        0x0003
+#define _SC_BC_STRING_MAX       0x0004
+#define _SC_CHILD_MAX           0x0005
+#define _SC_CLK_TCK             0x0006
+#define _SC_COLL_WEIGHTS_MAX    0x0007
+#define _SC_EXPR_NEST_MAX       0x0008
+#define _SC_LINE_MAX            0x0009
+#define _SC_NGROUPS_MAX         0x000a
+#define _SC_OPEN_MAX            0x000b
+#define _SC_PASS_MAX            0x000c
+#define _SC_2_C_BIND            0x000d
+#define _SC_2_C_DEV             0x000e
+#define _SC_2_C_VERSION         0x000f  /* Obsolescent in POSIX.1-2008, TODO: remove it. */
+#define _SC_2_CHAR_TERM         0x0010
+#define _SC_2_FORT_DEV          0x0011
+#define _SC_2_FORT_RUN          0x0012
+#define _SC_2_LOCALEDEF         0x0013
+#define _SC_2_SW_DEV            0x0014
+#define _SC_2_UPE               0x0015
+#define _SC_2_VERSION           0x0016
+#define _SC_JOB_CONTROL         0x0017
+#define _SC_SAVED_IDS           0x0018
+#define _SC_VERSION             0x0019
+#define _SC_RE_DUP_MAX          0x001a
+#define _SC_STREAM_MAX          0x001b
+#define _SC_TZNAME_MAX          0x001c
+#define _SC_XOPEN_CRYPT         0x001d
+#define _SC_XOPEN_ENH_I18N      0x001e
+#define _SC_XOPEN_SHM           0x001f
+#define _SC_XOPEN_VERSION       0x0020
+#define _SC_XOPEN_XCU_VERSION   0x0021  /* Obsolescent in POSIX.1-2008, TODO: remove it. */
+#define _SC_XOPEN_REALTIME      0x0022
+#define _SC_XOPEN_REALTIME_THREADS  0x0023
+#define _SC_XOPEN_LEGACY        0x0024
+#define _SC_ATEXIT_MAX          0x0025
+#define _SC_IOV_MAX             0x0026
+#define _SC_PAGESIZE            0x0027
+#define _SC_PAGE_SIZE           0x0028
+#define _SC_XOPEN_UNIX          0x0029
+#define _SC_XBS5_ILP32_OFF32    0x002a  /* Obsolescent in POSIX.1-2008, TODO: remove it. */
+#define _SC_XBS5_ILP32_OFFBIG   0x002b  /* Obsolescent in POSIX.1-2008, TODO: remove it. */
+#define _SC_XBS5_LP64_OFF64     0x002c  /* Obsolescent in POSIX.1-2008, TODO: remove it. */
+#define _SC_XBS5_LPBIG_OFFBIG   0x002d  /* Obsolescent in POSIX.1-2008, TODO: remove it. */
+#define _SC_AIO_LISTIO_MAX      0x002e
+#define _SC_AIO_MAX             0x002f
+#define _SC_AIO_PRIO_DELTA_MAX  0x0030
+#define _SC_DELAYTIMER_MAX      0x0031
+#define _SC_MQ_OPEN_MAX         0x0032
+#define _SC_MQ_PRIO_MAX         0x0033
+#define _SC_RTSIG_MAX           0x0034
+#define _SC_SEM_NSEMS_MAX       0x0035
+#define _SC_SEM_VALUE_MAX       0x0036
+#define _SC_SIGQUEUE_MAX        0x0037
+#define _SC_TIMER_MAX           0x0038
+#define _SC_ASYNCHRONOUS_IO     0x0039
+#define _SC_FSYNC               0x003a
+#define _SC_MAPPED_FILES        0x003b
+#define _SC_MEMLOCK             0x003c
+#define _SC_MEMLOCK_RANGE       0x003d
+#define _SC_MEMORY_PROTECTION   0x003e
+#define _SC_MESSAGE_PASSING     0x003f
+#define _SC_PRIORITIZED_IO      0x0040
+#define _SC_PRIORITY_SCHEDULING 0x0041
+#define _SC_REALTIME_SIGNALS    0x0042
+#define _SC_SEMAPHORES          0x0043
+#define _SC_SHARED_MEMORY_OBJECTS  0x0044
+#define _SC_SYNCHRONIZED_IO     0x0045
+#define _SC_TIMERS              0x0046
+#define _SC_GETGR_R_SIZE_MAX    0x0047
+#define _SC_GETPW_R_SIZE_MAX    0x0048
+#define _SC_LOGIN_NAME_MAX      0x0049
+#define _SC_THREAD_DESTRUCTOR_ITERATIONS  0x004a
+#define _SC_THREAD_KEYS_MAX     0x004b
+#define _SC_THREAD_STACK_MIN    0x004c
+#define _SC_THREAD_THREADS_MAX  0x004d
+#define _SC_TTY_NAME_MAX        0x004e
+
+#define _SC_THREADS                     0x004f
+#define _SC_THREAD_ATTR_STACKADDR       0x0050
+#define _SC_THREAD_ATTR_STACKSIZE       0x0051
+#define _SC_THREAD_PRIORITY_SCHEDULING  0x0052
+#define _SC_THREAD_PRIO_INHERIT         0x0053
+#define _SC_THREAD_PRIO_PROTECT         0x0054
+#define _SC_THREAD_SAFE_FUNCTIONS       0x0055
+
+#define _SC_NPROCESSORS_CONF            0x0060
+#define _SC_NPROCESSORS_ONLN            0x0061
+#define _SC_PHYS_PAGES                  0x0062
+#define _SC_AVPHYS_PAGES                0x0063
+#define _SC_MONOTONIC_CLOCK             0x0064
+
+#define _SC_2_PBS               0x0065
+#define _SC_2_PBS_ACCOUNTING    0x0066
+#define _SC_2_PBS_CHECKPOINT    0x0067
+#define _SC_2_PBS_LOCATE        0x0068
+#define _SC_2_PBS_MESSAGE       0x0069
+#define _SC_2_PBS_TRACK         0x006a
+#define _SC_ADVISORY_INFO       0x006b
+#define _SC_BARRIERS            0x006c
+#define _SC_CLOCK_SELECTION     0x006d
+#define _SC_CPUTIME             0x006e
+#define _SC_HOST_NAME_MAX       0x006f
+#define _SC_IPV6                0x0070
+#define _SC_RAW_SOCKETS         0x0071
+#define _SC_READER_WRITER_LOCKS 0x0072
+#define _SC_REGEXP              0x0073
+#define _SC_SHELL               0x0074
+#define _SC_SPAWN               0x0075
+#define _SC_SPIN_LOCKS          0x0076
+#define _SC_SPORADIC_SERVER     0x0077
+#define _SC_SS_REPL_MAX         0x0078
+#define _SC_SYMLOOP_MAX         0x0079
+#define _SC_THREAD_CPUTIME      0x007a
+#define _SC_THREAD_PROCESS_SHARED       0x007b
+#define _SC_THREAD_ROBUST_PRIO_INHERIT  0x007c
+#define _SC_THREAD_ROBUST_PRIO_PROTECT  0x007d
+#define _SC_THREAD_SPORADIC_SERVER      0x007e
+#define _SC_TIMEOUTS            0x007f
+#define _SC_TRACE               0x0080
+#define _SC_TRACE_EVENT_FILTER  0x0081
+#define _SC_TRACE_EVENT_NAME_MAX  0x0082
+#define _SC_TRACE_INHERIT       0x0083
+#define _SC_TRACE_LOG           0x0084
+#define _SC_TRACE_NAME_MAX      0x0085
+#define _SC_TRACE_SYS_MAX       0x0086
+#define _SC_TRACE_USER_EVENT_MAX  0x0087
+#define _SC_TYPED_MEMORY_OBJECTS  0x0088
+#define _SC_V7_ILP32_OFF32      0x0089
+#define _SC_V7_ILP32_OFFBIG     0x008a
+#define _SC_V7_LP64_OFF64       0x008b
+#define _SC_V7_LPBIG_OFFBIG     0x008c
+#define _SC_XOPEN_STREAMS       0x008d
+#define _SC_XOPEN_UUCP          0x008e
+
+#define _SC_LEVEL1_ICACHE_SIZE      0x008f
+#define _SC_LEVEL1_ICACHE_ASSOC     0x0090
+#define _SC_LEVEL1_ICACHE_LINESIZE  0x0091
+#define _SC_LEVEL1_DCACHE_SIZE      0x0092
+#define _SC_LEVEL1_DCACHE_ASSOC     0x0093
+#define _SC_LEVEL1_DCACHE_LINESIZE  0x0094
+#define _SC_LEVEL2_CACHE_SIZE       0x0095
+#define _SC_LEVEL2_CACHE_ASSOC      0x0096
+#define _SC_LEVEL2_CACHE_LINESIZE   0x0097
+#define _SC_LEVEL3_CACHE_SIZE       0x0098
+#define _SC_LEVEL3_CACHE_ASSOC      0x0099
+#define _SC_LEVEL3_CACHE_LINESIZE   0x009a
+#define _SC_LEVEL4_CACHE_SIZE       0x009b
+#define _SC_LEVEL4_CACHE_ASSOC      0x009c
+#define _SC_LEVEL4_CACHE_LINESIZE   0x009d
+
+__BEGIN_DECLS
+
+long sysconf(int __name);
+
+__END_DECLS
+
+#endif /* _SYS_SYSCONF_H_ */
diff --git a/libc/include/sys/sysconf.h b/libc/include/sys/sysconf.h
index ca32132..c9895f2 100644
--- a/libc/include/sys/sysconf.h
+++ b/libc/include/sys/sysconf.h
@@ -25,171 +25,9 @@
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
-#ifndef _SYS_SYSCONF_H_
-#define _SYS_SYSCONF_H_
 
-#include <sys/cdefs.h>
+// This file used to contain the declarations of sysconf and its associated constants.
+// No standard mentions a <sys/sysconf.h>, but there are enough users in vendor (and potential ones
+// in the NDK) to warrant not breaking source compatibility.
 
-__BEGIN_DECLS
-
-/* as listed by Posix sysconf() description */
-/* most of these will return -1 and ENOSYS  */
-
-#define _SC_ARG_MAX             0x0000
-#define _SC_BC_BASE_MAX         0x0001
-#define _SC_BC_DIM_MAX          0x0002
-#define _SC_BC_SCALE_MAX        0x0003
-#define _SC_BC_STRING_MAX       0x0004
-#define _SC_CHILD_MAX           0x0005
-#define _SC_CLK_TCK             0x0006
-#define _SC_COLL_WEIGHTS_MAX    0x0007
-#define _SC_EXPR_NEST_MAX       0x0008
-#define _SC_LINE_MAX            0x0009
-#define _SC_NGROUPS_MAX         0x000a
-#define _SC_OPEN_MAX            0x000b
-#define _SC_PASS_MAX            0x000c
-#define _SC_2_C_BIND            0x000d
-#define _SC_2_C_DEV             0x000e
-#define _SC_2_C_VERSION         0x000f  /* Obsolescent in POSIX.1-2008, TODO: remove it. */
-#define _SC_2_CHAR_TERM         0x0010
-#define _SC_2_FORT_DEV          0x0011
-#define _SC_2_FORT_RUN          0x0012
-#define _SC_2_LOCALEDEF         0x0013
-#define _SC_2_SW_DEV            0x0014
-#define _SC_2_UPE               0x0015
-#define _SC_2_VERSION           0x0016
-#define _SC_JOB_CONTROL         0x0017
-#define _SC_SAVED_IDS           0x0018
-#define _SC_VERSION             0x0019
-#define _SC_RE_DUP_MAX          0x001a
-#define _SC_STREAM_MAX          0x001b
-#define _SC_TZNAME_MAX          0x001c
-#define _SC_XOPEN_CRYPT         0x001d
-#define _SC_XOPEN_ENH_I18N      0x001e
-#define _SC_XOPEN_SHM           0x001f
-#define _SC_XOPEN_VERSION       0x0020
-#define _SC_XOPEN_XCU_VERSION   0x0021  /* Obsolescent in POSIX.1-2008, TODO: remove it. */
-#define _SC_XOPEN_REALTIME      0x0022
-#define _SC_XOPEN_REALTIME_THREADS  0x0023
-#define _SC_XOPEN_LEGACY        0x0024
-#define _SC_ATEXIT_MAX          0x0025
-#define _SC_IOV_MAX             0x0026
-#define _SC_PAGESIZE            0x0027
-#define _SC_PAGE_SIZE           0x0028
-#define _SC_XOPEN_UNIX          0x0029
-#define _SC_XBS5_ILP32_OFF32    0x002a  /* Obsolescent in POSIX.1-2008, TODO: remove it. */
-#define _SC_XBS5_ILP32_OFFBIG   0x002b  /* Obsolescent in POSIX.1-2008, TODO: remove it. */
-#define _SC_XBS5_LP64_OFF64     0x002c  /* Obsolescent in POSIX.1-2008, TODO: remove it. */
-#define _SC_XBS5_LPBIG_OFFBIG   0x002d  /* Obsolescent in POSIX.1-2008, TODO: remove it. */
-#define _SC_AIO_LISTIO_MAX      0x002e
-#define _SC_AIO_MAX             0x002f
-#define _SC_AIO_PRIO_DELTA_MAX  0x0030
-#define _SC_DELAYTIMER_MAX      0x0031
-#define _SC_MQ_OPEN_MAX         0x0032
-#define _SC_MQ_PRIO_MAX         0x0033
-#define _SC_RTSIG_MAX           0x0034
-#define _SC_SEM_NSEMS_MAX       0x0035
-#define _SC_SEM_VALUE_MAX       0x0036
-#define _SC_SIGQUEUE_MAX        0x0037
-#define _SC_TIMER_MAX           0x0038
-#define _SC_ASYNCHRONOUS_IO     0x0039
-#define _SC_FSYNC               0x003a
-#define _SC_MAPPED_FILES        0x003b
-#define _SC_MEMLOCK             0x003c
-#define _SC_MEMLOCK_RANGE       0x003d
-#define _SC_MEMORY_PROTECTION   0x003e
-#define _SC_MESSAGE_PASSING     0x003f
-#define _SC_PRIORITIZED_IO      0x0040
-#define _SC_PRIORITY_SCHEDULING 0x0041
-#define _SC_REALTIME_SIGNALS    0x0042
-#define _SC_SEMAPHORES          0x0043
-#define _SC_SHARED_MEMORY_OBJECTS  0x0044
-#define _SC_SYNCHRONIZED_IO     0x0045
-#define _SC_TIMERS              0x0046
-#define _SC_GETGR_R_SIZE_MAX    0x0047
-#define _SC_GETPW_R_SIZE_MAX    0x0048
-#define _SC_LOGIN_NAME_MAX      0x0049
-#define _SC_THREAD_DESTRUCTOR_ITERATIONS  0x004a
-#define _SC_THREAD_KEYS_MAX     0x004b
-#define _SC_THREAD_STACK_MIN    0x004c
-#define _SC_THREAD_THREADS_MAX  0x004d
-#define _SC_TTY_NAME_MAX        0x004e
-
-#define _SC_THREADS                     0x004f
-#define _SC_THREAD_ATTR_STACKADDR       0x0050
-#define _SC_THREAD_ATTR_STACKSIZE       0x0051
-#define _SC_THREAD_PRIORITY_SCHEDULING  0x0052
-#define _SC_THREAD_PRIO_INHERIT         0x0053
-#define _SC_THREAD_PRIO_PROTECT         0x0054
-#define _SC_THREAD_SAFE_FUNCTIONS       0x0055
-
-#define _SC_NPROCESSORS_CONF            0x0060
-#define _SC_NPROCESSORS_ONLN            0x0061
-#define _SC_PHYS_PAGES                  0x0062
-#define _SC_AVPHYS_PAGES                0x0063
-#define _SC_MONOTONIC_CLOCK             0x0064
-
-#define _SC_2_PBS               0x0065
-#define _SC_2_PBS_ACCOUNTING    0x0066
-#define _SC_2_PBS_CHECKPOINT    0x0067
-#define _SC_2_PBS_LOCATE        0x0068
-#define _SC_2_PBS_MESSAGE       0x0069
-#define _SC_2_PBS_TRACK         0x006a
-#define _SC_ADVISORY_INFO       0x006b
-#define _SC_BARRIERS            0x006c
-#define _SC_CLOCK_SELECTION     0x006d
-#define _SC_CPUTIME             0x006e
-#define _SC_HOST_NAME_MAX       0x006f
-#define _SC_IPV6                0x0070
-#define _SC_RAW_SOCKETS         0x0071
-#define _SC_READER_WRITER_LOCKS 0x0072
-#define _SC_REGEXP              0x0073
-#define _SC_SHELL               0x0074
-#define _SC_SPAWN               0x0075
-#define _SC_SPIN_LOCKS          0x0076
-#define _SC_SPORADIC_SERVER     0x0077
-#define _SC_SS_REPL_MAX         0x0078
-#define _SC_SYMLOOP_MAX         0x0079
-#define _SC_THREAD_CPUTIME      0x007a
-#define _SC_THREAD_PROCESS_SHARED       0x007b
-#define _SC_THREAD_ROBUST_PRIO_INHERIT  0x007c
-#define _SC_THREAD_ROBUST_PRIO_PROTECT  0x007d
-#define _SC_THREAD_SPORADIC_SERVER      0x007e
-#define _SC_TIMEOUTS            0x007f
-#define _SC_TRACE               0x0080
-#define _SC_TRACE_EVENT_FILTER  0x0081
-#define _SC_TRACE_EVENT_NAME_MAX  0x0082
-#define _SC_TRACE_INHERIT       0x0083
-#define _SC_TRACE_LOG           0x0084
-#define _SC_TRACE_NAME_MAX      0x0085
-#define _SC_TRACE_SYS_MAX       0x0086
-#define _SC_TRACE_USER_EVENT_MAX  0x0087
-#define _SC_TYPED_MEMORY_OBJECTS  0x0088
-#define _SC_V7_ILP32_OFF32      0x0089
-#define _SC_V7_ILP32_OFFBIG     0x008a
-#define _SC_V7_LP64_OFF64       0x008b
-#define _SC_V7_LPBIG_OFFBIG     0x008c
-#define _SC_XOPEN_STREAMS       0x008d
-#define _SC_XOPEN_UUCP          0x008e
-
-#define _SC_LEVEL1_ICACHE_SIZE      0x008f
-#define _SC_LEVEL1_ICACHE_ASSOC     0x0090
-#define _SC_LEVEL1_ICACHE_LINESIZE  0x0091
-#define _SC_LEVEL1_DCACHE_SIZE      0x0092
-#define _SC_LEVEL1_DCACHE_ASSOC     0x0093
-#define _SC_LEVEL1_DCACHE_LINESIZE  0x0094
-#define _SC_LEVEL2_CACHE_SIZE       0x0095
-#define _SC_LEVEL2_CACHE_ASSOC      0x0096
-#define _SC_LEVEL2_CACHE_LINESIZE   0x0097
-#define _SC_LEVEL3_CACHE_SIZE       0x0098
-#define _SC_LEVEL3_CACHE_ASSOC      0x0099
-#define _SC_LEVEL3_CACHE_LINESIZE   0x009a
-#define _SC_LEVEL4_CACHE_SIZE       0x009b
-#define _SC_LEVEL4_CACHE_ASSOC      0x009c
-#define _SC_LEVEL4_CACHE_LINESIZE   0x009d
-
-long sysconf(int);
-
-__END_DECLS
-
-#endif /* _SYS_SYSCONF_H_ */
+#include <bits/sysconf.h>
diff --git a/libc/include/unistd.h b/libc/include/unistd.h
index 725cef5..ea6c8a1 100644
--- a/libc/include/unistd.h
+++ b/libc/include/unistd.h
@@ -33,13 +33,13 @@
 #include <sys/cdefs.h>
 #include <sys/types.h>
 #include <sys/select.h>
-#include <sys/sysconf.h>
 
 #include <bits/fcntl.h>
 #include <bits/getopt.h>
 #include <bits/ioctl.h>
 #include <bits/lockf.h>
 #include <bits/posix_limits.h>
+#include <bits/sysconf.h>
 
 __BEGIN_DECLS
 
@@ -214,8 +214,6 @@
 
 extern int acct(const char* __filepath);
 
-long sysconf(int __name);
-
 #if __ANDROID_API__ >= 21
 int getpagesize(void);
 #else