diff --git a/posix/conf.list b/posix/conf.list
index 000b908..0a17666 100644
--- a/posix/conf.list
+++ b/posix/conf.list
@@ -1,7 +1,8 @@
 # Configuration variables identified by getconf.  The heading of each section
-# is of the format TYPE:PREFIX with the opening curly brace on the same line.
-# TYPE can either be SYSCONF, PATHCONF, CONFSTR or SPEC.  Variable names are
-# put one on each line with a curly brace on its own line ending the section.
+# is of the format TYPE:PREFIX:SC_PREFIX with the opening curly brace on the
+# same line.  TYPE can either be SYSCONF, PATHCONF, CONFSTR or SPEC.  In the
+# absence of SC_PREFIX, _SC is used as the SC_PREFIX.  Variable names are put
+# one on each line with a curly brace on its own line ending the section.
 
 SPEC:POSIX {
   V6_ILP32_OFF32
@@ -103,7 +104,7 @@ SYSCONF:POSIX {
   RAW_SOCKETS
 }
 
-SPEC:XBS5 {
+SPEC:XBS5:_SC_XBS5 {
   ILP32_OFF32
   ILP32_OFFBIG
   LP64_OFF64
diff --git a/posix/confstr.c b/posix/confstr.c
index 1accfee..0400d7f 100644
--- a/posix/confstr.c
+++ b/posix/confstr.c
@@ -21,7 +21,9 @@
 #include <string.h>
 #include <confstr.h>
 #include "../version.h"
-#include "confdefs.h"
+
+#define NEED_SPEC_ARRAY 0
+#include <confdefs.h>
 
 /* If BUF is not NULL and LEN > 0, fill in at most LEN - 1 bytes
    of BUF with the value corresponding to NAME and zero-terminate BUF.
diff --git a/posix/getconf.c b/posix/getconf.c
index 14d51d8..3c08688 100644
--- a/posix/getconf.c
+++ b/posix/getconf.c
@@ -26,6 +26,9 @@
 #include "../version.h"
 #define PACKAGE _libc_intl_domainname
 
+#define NEED_SPEC_ARRAY 1
+#include <confdefs.h>
+
 struct conf
   {
     const char *name;
@@ -387,23 +390,6 @@ static const struct conf vars[] =
   };
 
 
-static const struct { const char *name; int num; } specs[] =
-  {
-    { "XBS5_ILP32_OFF32", _SC_XBS5_ILP32_OFF32 },
-    { "XBS5_ILP32_OFFBIG", _SC_XBS5_ILP32_OFFBIG },
-    { "XBS5_LP64_OFF64", _SC_XBS5_LP64_OFF64 },
-    { "XBS5_LPBIG_OFFBIG", _SC_XBS5_LPBIG_OFFBIG },
-    { "POSIX_V6_ILP32_OFF32", _SC_V6_ILP32_OFF32 },
-    { "POSIX_V6_ILP32_OFFBIG", _SC_V6_ILP32_OFFBIG },
-    { "POSIX_V6_LP64_OFF64", _SC_V6_LP64_OFF64 },
-    { "POSIX_V6_LPBIG_OFFBIG", _SC_V6_LPBIG_OFFBIG },
-    { "POSIX_V7_ILP32_OFF32", _SC_V7_ILP32_OFF32 },
-    { "POSIX_V7_ILP32_OFFBIG", _SC_V7_ILP32_OFFBIG },
-    { "POSIX_V7_LP64_OFF64", _SC_V7_LP64_OFF64 },
-    { "POSIX_V7_LPBIG_OFFBIG", _SC_V7_LPBIG_OFFBIG },
-  };
-static const int nspecs = sizeof (specs) / sizeof (specs[0]);
-
 extern const char *__progname;
 
 
diff --git a/posix/posix-envs.def b/posix/posix-envs.def
index 9047d0c..0b33e02 100644
--- a/posix/posix-envs.def
+++ b/posix/posix-envs.def
@@ -42,7 +42,8 @@
    defined.  These are called with arguments V5, V6, V7 before and
    after the relevant groups of environments.  */
 
-#include "confdefs.h"
+#define NEED_SPEC_ARRAY 0
+#include <confdefs.h>
 
 START_ENV_GROUP (V7)
 
diff --git a/scripts/gen-conf.awk b/scripts/gen-conf.awk
index 45a4d44..1370646 100644
--- a/scripts/gen-conf.awk
+++ b/scripts/gen-conf.awk
@@ -17,12 +17,17 @@ $2 == "{" {
   split ($1, arr, ":")
   type = arr[1]
   prefix = arr[2]
+  if (arr[3] != "")
+    sc_prefix = arr[3]
+  else
+    sc_prefix = "_SC"
   next
 }
 
 $1 == "}" {
   prefix = ""
   type = ""
+  sc_prefix = ""
   next
 }
 
@@ -37,6 +42,7 @@ $1 == "}" {
   # CONFSTR: A configuration string
   # SYSCONF: A numeric value
   # SPEC: A specification
+  sc_prefixes[prefix][$1] = sc_prefix
   conf[prefix][$1] = type
 }
 
@@ -58,6 +64,26 @@ ENDFILE {
 	printf "# endif\n"
       }
       printf "#endif\n\n"
+
+      # Build a name -> sysconf number associative array to print a C array at
+      # the end.
+      if (conf[p][c] == "SPEC") {
+	name = sprintf ("%s_%s", p, c)
+	num = sprintf ("%s_%s", sc_prefixes[p][c], c)
+	spec[name] = num
+      }
     }
   }
+
+  # Print the specification array.  Define the macro NEED_SPEC_ARRAY before
+  # including confdefs.h to make it available in the compilation unit.
+  print "#if NEED_SPEC_ARRAY"
+  print "static const struct { const char *name; int num; } specs[] ="
+  print "  {"
+  for (s in spec) {
+    printf "    { \"%s\", %s },\n", s, spec[s]
+  }
+  print "  };"
+  print "static const int nspecs = sizeof (specs) / sizeof (specs[0]);"
+  print "#endif"
 }
diff --git a/sysdeps/posix/sysconf.c b/sysdeps/posix/sysconf.c
index c7b748b..bff59f4 100644
--- a/sysdeps/posix/sysconf.c
+++ b/sysdeps/posix/sysconf.c
@@ -31,6 +31,7 @@
 #include <sys/types.h>
 #include <regex.h>
 
+#define NEED_SPEC_ARRAY 0
 #include <confdefs.h>
 
 
