diff --git a/libc/bionic/sysconf.cpp b/libc/bionic/sysconf.cpp
index 2df6acc..67f48e7 100644
--- a/libc/bionic/sysconf.cpp
+++ b/libc/bionic/sysconf.cpp
@@ -29,8 +29,10 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <limits.h>
+#include <linux/uio.h>  // For UIO_MAXIOV.
 #include <pthread.h>
 #include <stdio.h>  // For FOPEN_MAX.
+#include <sys/auxv.h>
 #include <sys/sysconf.h>
 #include <sys/sysinfo.h>
 #include <time.h>
@@ -38,33 +40,6 @@
 
 #include "private/bionic_tls.h"
 
-/* seems to be the default on Linux, per the GLibc sources and my own digging */
-
-#define  SYSTEM_CLK_TCK         100
-#define  SYSTEM_IOV_MAX         1024
-#define  SYSTEM_DELAYTIMER_MAX  2147483647
-#define  SYSTEM_MQ_OPEN_MAX     8
-#define  SYSTEM_MQ_PRIO_MAX     32768
-#define  SYSTEM_SEM_NSEMS_MAX   256
-#define  SYSTEM_SIGQUEUE_MAX    32
-#define  SYSTEM_TIMER_MAX       32
-#define  SYSTEM_LOGIN_NAME_MAX  256
-#define  SYSTEM_TTY_NAME_MAX    32
-
-/* the following depends on our implementation */
-#define  SYSTEM_ATEXIT_MAX          65536    /* our implementation is unlimited */
-#define  SYSTEM_THREAD_THREADS_MAX  2048     /* really unlimited */
-
-#define  SYSTEM_2_C_BIND     _POSIX_VERSION  /* Posix C binding version */
-#define  SYSTEM_2_C_VER      _POSIX2_C_VERSION
-#define  SYSTEM_2_C_DEV      -1       /* Posix C development tools unsupported on the device */
-#define  SYSTEM_2_FORT_DEV   -1       /* Fortran development unsupported */
-#define  SYSTEM_2_FORT_RUN   -1       /* Fortran runtime unsupported */
-#define  SYSTEM_2_SW_DEV     -1       /* posix software dev utilities unsupported */
-#define  SYSTEM_2_LOCALEDEF  -1       /* localedef() unimplemented */
-#define  SYSTEM_2_UPE        -1       /* No UPE for you ! (User Portability Utilities) */
-#define  SYSTEM_2_VERSION    -1       /* No posix command-line tools */
-
 static int __sysconf_monotonic_clock() {
   timespec t;
   int rc = clock_getres(CLOCK_MONOTONIC, &t);
@@ -73,103 +48,135 @@
 
 long sysconf(int name) {
   switch (name) {
-    case _SC_ARG_MAX:           return _POSIX_ARG_MAX;
+    case _SC_ARG_MAX:           return ARG_MAX;
+    case _SC_BC_BASE_MAX:       return _POSIX2_BC_BASE_MAX;   // Minimum requirement.
+    case _SC_BC_DIM_MAX:        return _POSIX2_BC_DIM_MAX;    // Minimum requirement.
+    case _SC_BC_SCALE_MAX:      return _POSIX2_BC_SCALE_MAX;  // Minimum requirement.
+    case _SC_BC_STRING_MAX:     return _POSIX2_BC_STRING_MAX; // Minimum requirement.
     case _SC_CHILD_MAX:         return CHILD_MAX;
-    case _SC_CLK_TCK:           return SYSTEM_CLK_TCK;
-    case _SC_LINE_MAX:          return _POSIX2_LINE_MAX;
+    case _SC_CLK_TCK:           return static_cast<long>(getauxval(AT_CLKTCK));
+    case _SC_COLL_WEIGHTS_MAX:  return _POSIX2_COLL_WEIGHTS_MAX;  // Minimum requirement.
+    case _SC_EXPR_NEST_MAX:     return _POSIX2_EXPR_NEST_MAX;     // Minimum requirement.
+    case _SC_LINE_MAX:          return _POSIX2_LINE_MAX;          // Minimum requirement.
     case _SC_NGROUPS_MAX:       return NGROUPS_MAX;
     case _SC_OPEN_MAX:          return OPEN_MAX;
     case _SC_PASS_MAX:          return PASS_MAX;
-    case _SC_2_C_BIND:          return SYSTEM_2_C_BIND;
-    case _SC_2_C_DEV:           return SYSTEM_2_C_DEV;
-    case _SC_2_C_VERSION:       return SYSTEM_2_C_VER;
-    //case _SC_2_CHAR_TERM:         return ;
-    case _SC_2_FORT_DEV:        return SYSTEM_2_FORT_DEV;
-    case _SC_2_FORT_RUN:        return SYSTEM_2_FORT_RUN;
-    case _SC_2_LOCALEDEF:       return SYSTEM_2_LOCALEDEF;
-    case _SC_2_SW_DEV:          return SYSTEM_2_SW_DEV;
-    case _SC_2_UPE:             return SYSTEM_2_UPE;
-    case _SC_2_VERSION:         return SYSTEM_2_VERSION;
+    case _SC_2_C_BIND:          return _POSIX2_C_BIND;
+    case _SC_2_C_DEV:           return _POSIX2_C_DEV;
+    case _SC_2_CHAR_TERM:       return _POSIX2_CHAR_TERM;
+    case _SC_2_FORT_DEV:        return -1;
+    case _SC_2_FORT_RUN:        return -1;
+    case _SC_2_LOCALEDEF:       return _POSIX2_LOCALEDEF;
+    case _SC_2_SW_DEV:          return _POSIX2_SW_DEV;
+    case _SC_2_UPE:             return _POSIX2_UPE;
+    case _SC_2_VERSION:         return _POSIX2_VERSION;
     case _SC_JOB_CONTROL:       return _POSIX_JOB_CONTROL;
     case _SC_SAVED_IDS:         return _POSIX_SAVED_IDS;
     case _SC_VERSION:           return _POSIX_VERSION;
-    case _SC_RE_DUP_MAX:        return _POSIX_RE_DUP_MAX;
+    case _SC_RE_DUP_MAX:        return _POSIX_RE_DUP_MAX;         // Minimum requirement.
     case _SC_STREAM_MAX:        return FOPEN_MAX;
-    case _SC_TZNAME_MAX:        return _POSIX_TZNAME_MAX;
+    case _SC_TZNAME_MAX:        return _POSIX_TZNAME_MAX;         // Minimum requirement.
     case _SC_XOPEN_CRYPT:       return _XOPEN_CRYPT;
     case _SC_XOPEN_ENH_I18N:    return _XOPEN_ENH_I18N;
-    //case _SC_XOPEN_SHM:         return _XOPEN_SHM;
+    case _SC_XOPEN_SHM:         return _XOPEN_SHM;
     case _SC_XOPEN_VERSION:     return _XOPEN_VERSION;
-    case _SC_XOPEN_XCU_VERSION: return _XOPEN_XCU_VERSION;
     case _SC_XOPEN_REALTIME:    return _XOPEN_REALTIME;
     case _SC_XOPEN_REALTIME_THREADS: return _XOPEN_REALTIME_THREADS;
     case _SC_XOPEN_LEGACY:      return _XOPEN_LEGACY;
-    case _SC_ATEXIT_MAX:        return SYSTEM_ATEXIT_MAX;
-    case _SC_IOV_MAX:           return SYSTEM_IOV_MAX;
+    case _SC_ATEXIT_MAX:        return LONG_MAX;    // Unlimited.
+    case _SC_IOV_MAX:           return UIO_MAXIOV;
 
-    case _SC_PAGESIZE:
-    case _SC_PAGE_SIZE:
-        return PAGE_SIZE;
-
+    case _SC_PAGESIZE:          // Fall through, PAGESIZE and PAGE_SIZE always hold the same value.
+    case _SC_PAGE_SIZE:         return PAGE_SIZE;
     case _SC_XOPEN_UNIX:        return _XOPEN_UNIX;
-
-    // XXX: TODO: XBS5 nonsense
-
-    //case _SC_AIO_LISTIO_MAX:       return AIO_LISTIO_MAX;
-    //case _SC_AIO_MAX:              return AIO_MAX;
-    //case _SC_AIO_PRIO_DELTA_MAX:   return AIO_PRIO_DELTA_MAX;
-    case _SC_DELAYTIMER_MAX:    return SYSTEM_DELAYTIMER_MAX;
-    case _SC_MQ_OPEN_MAX:       return SYSTEM_MQ_OPEN_MAX;
-    case _SC_MQ_PRIO_MAX:       return SYSTEM_MQ_PRIO_MAX;
+    case _SC_AIO_LISTIO_MAX:    return _POSIX_AIO_LISTIO_MAX;     // Minimum requirement.
+    case _SC_AIO_MAX:           return _POSIX_AIO_MAX;            // Minimum requirement.
+    case _SC_AIO_PRIO_DELTA_MAX:return 0;                         // Minimum requirement.
+    case _SC_DELAYTIMER_MAX:    return INT_MAX;
+    case _SC_MQ_OPEN_MAX:       return _POSIX_MQ_OPEN_MAX;        // Minimum requirement.
+    case _SC_MQ_PRIO_MAX:       return _POSIX_MQ_PRIO_MAX;        // Minimum requirement.
     case _SC_RTSIG_MAX:         return RTSIG_MAX;
-    case _SC_SEM_NSEMS_MAX:     return SYSTEM_SEM_NSEMS_MAX;
+    case _SC_SEM_NSEMS_MAX:     return _POSIX_SEM_NSEMS_MAX;      // Minimum requirement.
     case _SC_SEM_VALUE_MAX:     return SEM_VALUE_MAX;
-    case _SC_SIGQUEUE_MAX:      return SYSTEM_SIGQUEUE_MAX;
-    case _SC_TIMER_MAX:         return SYSTEM_TIMER_MAX;
-    //case _SC_ASYNCHRONOUS_IO:   return _POSIX_ASYNCHRONOUS_IO;
+    case _SC_SIGQUEUE_MAX:      return _POSIX_SIGQUEUE_MAX;       // Minimum requirement.
+    case _SC_TIMER_MAX:         return _POSIX_TIMER_MAX;          // Minimum requirement.
+    case _SC_ASYNCHRONOUS_IO:   return _POSIX_ASYNCHRONOUS_IO;
     case _SC_FSYNC:             return _POSIX_FSYNC;
     case _SC_MAPPED_FILES:      return _POSIX_MAPPED_FILES;
-    //case _SC_MEMLOCK:           return _POSIX_MEMLOCK;
-    //case _SC_MEMLOCK_RANGE:     return _POSIX_MEMLOCK_RANGE;
-    //case _SC_MEMORY_PROTECTION: return _POSIX_MEMORY_PROTECTION;
-    //case _SC_MESSAGE_PASSING:   return _POSIX_MESSAGE_PASSING;
-    //case _SC_PRIORITIZED_IO:    return _POSIX_PRIORITIZED_IO;
+    case _SC_MEMLOCK:           return _POSIX_MEMLOCK;
+    case _SC_MEMLOCK_RANGE:     return _POSIX_MEMLOCK_RANGE;
+    case _SC_MEMORY_PROTECTION: return _POSIX_MEMORY_PROTECTION;
+    case _SC_MESSAGE_PASSING:   return _POSIX_MESSAGE_PASSING;
+    case _SC_PRIORITIZED_IO:    return _POSIX_PRIORITIZED_IO;
     case _SC_PRIORITY_SCHEDULING:  return _POSIX_PRIORITY_SCHEDULING;
     case _SC_REALTIME_SIGNALS:  return _POSIX_REALTIME_SIGNALS;
     case _SC_SEMAPHORES:        return _POSIX_SEMAPHORES;
-    //case _SC_SHARED_MEMORY_OBJECTS:  return _POSIX_SHARED_MEMORY_OBJECTS;
+    case _SC_SHARED_MEMORY_OBJECTS:  return _POSIX_SHARED_MEMORY_OBJECTS;
     case _SC_SYNCHRONIZED_IO:   return _POSIX_SYNCHRONIZED_IO;
     case _SC_TIMERS:            return _POSIX_TIMERS;
-
-    case _SC_GETGR_R_SIZE_MAX: return 1024;
-    case _SC_GETPW_R_SIZE_MAX: return 1024;
-
-    case _SC_LOGIN_NAME_MAX:    return SYSTEM_LOGIN_NAME_MAX;
-
-    case _SC_THREAD_DESTRUCTOR_ITERATIONS:
-      return _POSIX_THREAD_DESTRUCTOR_ITERATIONS;
-
-    case _SC_THREAD_KEYS_MAX:
-      return (BIONIC_TLS_SLOTS - TLS_SLOT_FIRST_USER_SLOT - BIONIC_TLS_RESERVED_SLOTS);
-
+    case _SC_GETGR_R_SIZE_MAX:  return 1024;
+    case _SC_GETPW_R_SIZE_MAX:  return 1024;
+    case _SC_LOGIN_NAME_MAX:    return 256;   // Seems default on linux.
+    case _SC_THREAD_DESTRUCTOR_ITERATIONS: return PTHREAD_DESTRUCTOR_ITERATIONS;
+    case _SC_THREAD_KEYS_MAX:   return PTHREAD_KEYS_MAX;
     case _SC_THREAD_STACK_MIN:    return PTHREAD_STACK_MIN;
-    case _SC_THREAD_THREADS_MAX:  return SYSTEM_THREAD_THREADS_MAX;
-    case _SC_TTY_NAME_MAX:        return SYSTEM_TTY_NAME_MAX;
+    case _SC_THREAD_THREADS_MAX:  return PTHREAD_THREADS_MAX;
+    case _SC_TTY_NAME_MAX:        return 32;  // Seems default on linux.
     case _SC_THREADS:             return _POSIX_THREADS;
-
-    case _SC_THREAD_ATTR_STACKADDR:   return -1; // Removed in POSIX 2008
-    case _SC_THREAD_ATTR_STACKSIZE:   return -1; // Removed in POSIX 2008
-
-    //case _SC_THREAD_PRIORITY_SCHEDULING:  return _POSIX_THREAD_PRIORITY_SCHEDULING;
-    case _SC_THREAD_PRIO_INHERIT:         return _POSIX_THREAD_PRIO_INHERIT;
+    case _SC_THREAD_ATTR_STACKADDR:   return _POSIX_THREAD_ATTR_STACKADDR;
+    case _SC_THREAD_ATTR_STACKSIZE:   return _POSIX_THREAD_ATTR_STACKSIZE;
+    case _SC_THREAD_PRIORITY_SCHEDULING:  return _POSIX_THREAD_PRIORITY_SCHEDULING;
+    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 __sysconf_monotonic_clock();
+    case _SC_THREAD_SAFE_FUNCTIONS:  return _POSIX_THREAD_SAFE_FUNCTIONS;
     case _SC_NPROCESSORS_CONF:  return get_nprocs_conf();
     case _SC_NPROCESSORS_ONLN:  return get_nprocs();
     case _SC_PHYS_PAGES:        return get_phys_pages();
     case _SC_AVPHYS_PAGES:      return get_avphys_pages();
+    case _SC_MONOTONIC_CLOCK:   return __sysconf_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.
+    case _SC_2_PBS_CHECKPOINT:  return -1;     // Obsolescent in POSIX.1-2008.
+    case _SC_2_PBS_LOCATE:      return -1;     // Obsolescent in POSIX.1-2008.
+    case _SC_2_PBS_MESSAGE:     return -1;     // Obsolescent in POSIX.1-2008.
+    case _SC_2_PBS_TRACK:       return -1;     // Obsolescent in POSIX.1-2008.
+    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_CPUTIME;
+    case _SC_HOST_NAME_MAX:     return _POSIX_HOST_NAME_MAX;    // Minimum requirement.
+    case _SC_IPV6:              return _POSIX_IPV6;
+    case _SC_RAW_SOCKETS:       return _POSIX_RAW_SOCKETS;
+    case _SC_READER_WRITER_LOCKS: return _POSIX_READER_WRITER_LOCKS;
+    case _SC_REGEXP:            return _POSIX_REGEXP;
+    case _SC_SHELL:             return _POSIX_SHELL;
+    case _SC_SPAWN:             return _POSIX_SPAWN;
+    case _SC_SPIN_LOCKS:        return _POSIX_SPIN_LOCKS;
+    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_THREAD_CPUTIME;
+    case _SC_THREAD_PROCESS_SHARED: return _POSIX_THREAD_PROCESS_SHARED;
+    case _SC_THREAD_ROBUST_PRIO_INHERIT:  return _POSIX_THREAD_ROBUST_PRIO_INHERIT;
+    case _SC_THREAD_ROBUST_PRIO_PROTECT:  return _POSIX_THREAD_ROBUST_PRIO_PROTECT;
+    case _SC_THREAD_SPORADIC_SERVER:      return _POSIX_THREAD_SPORADIC_SERVER;
+    case _SC_TIMEOUTS:          return _POSIX_TIMEOUTS;
+    case _SC_TRACE:             return -1;             // Obsolescent in POSIX.1-2008.
+    case _SC_TRACE_EVENT_FILTER:      return -1;       // Obsolescent in POSIX.1-2008.
+    case _SC_TRACE_EVENT_NAME_MAX:    return -1;
+    case _SC_TRACE_INHERIT:     return -1;             // Obsolescent in POSIX.1-2008.
+    case _SC_TRACE_LOG:         return -1;             // Obsolescent in POSIX.1-2008.
+    case _SC_TRACE_NAME_MAX:    return -1;
+    case _SC_TRACE_SYS_MAX:     return -1;
+    case _SC_TRACE_USER_EVENT_MAX:    return -1;
+    case _SC_TYPED_MEMORY_OBJECTS:    return _POSIX_TYPED_MEMORY_OBJECTS;
+    case _SC_V7_ILP32_OFF32:    return _POSIX_V7_ILP32_OFF32;
+    case _SC_V7_ILP32_OFFBIG:   return _POSIX_V7_ILP32_OFFBIG;
+    case _SC_V7_LP64_OFF64:     return _POSIX_V7_LP64_OFF64;
+    case _SC_V7_LPBIG_OFFBIG:   return _POSIX_V7_LPBIG_OFFBIG;
+    case _SC_XOPEN_STREAMS:     return -1;            // Obsolescent in POSIX.1-2008.
+    case _SC_XOPEN_UUCP:        return -1;
 
     default:
       // Posix says EINVAL is the only error that shall be returned,