diff --git a/configure b/configure
index 69a3c1c0db8..48440ea3b57 100755
--- a/configure
+++ b/configure
@@ -23423,6 +23423,143 @@ _ACEOF
 fi
 done
 
+# strto[u]ll may exist but not be declared
+{ $as_echo "$as_me:$LINENO: checking whether strtoll is declared" >&5
+$as_echo_n "checking whether strtoll is declared... " >&6; }
+if test "${ac_cv_have_decl_strtoll+set}" = set; then
+  $as_echo_n "(cached) " >&6
+else
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+$ac_includes_default
+int
+main ()
+{
+#ifndef strtoll
+  (void) strtoll;
+#endif
+
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval ac_try_echo="\"\$as_me:$LINENO: $ac_try_echo\""
+$as_echo "$ac_try_echo") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+  ac_cv_have_decl_strtoll=yes
+else
+  $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	ac_cv_have_decl_strtoll=no
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:$LINENO: result: $ac_cv_have_decl_strtoll" >&5
+$as_echo "$ac_cv_have_decl_strtoll" >&6; }
+if test "x$ac_cv_have_decl_strtoll" = x""yes; then
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_STRTOLL 1
+_ACEOF
+
+
+else
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_STRTOLL 0
+_ACEOF
+
+
+fi
+{ $as_echo "$as_me:$LINENO: checking whether strtoull is declared" >&5
+$as_echo_n "checking whether strtoull is declared... " >&6; }
+if test "${ac_cv_have_decl_strtoull+set}" = set; then
+  $as_echo_n "(cached) " >&6
+else
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+$ac_includes_default
+int
+main ()
+{
+#ifndef strtoull
+  (void) strtoull;
+#endif
+
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval ac_try_echo="\"\$as_me:$LINENO: $ac_try_echo\""
+$as_echo "$ac_try_echo") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+  ac_cv_have_decl_strtoull=yes
+else
+  $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	ac_cv_have_decl_strtoull=no
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:$LINENO: result: $ac_cv_have_decl_strtoull" >&5
+$as_echo "$ac_cv_have_decl_strtoull" >&6; }
+if test "x$ac_cv_have_decl_strtoull" = x""yes; then
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_STRTOULL 1
+_ACEOF
+
+
+else
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_STRTOULL 0
+_ACEOF
+
+
+fi
+
+
 
 { $as_echo "$as_me:$LINENO: checking for builtin locking functions" >&5
 $as_echo_n "checking for builtin locking functions... " >&6; }
diff --git a/configure.in b/configure.in
index 6c4b56667b5..7f11500e4f6 100644
--- a/configure.in
+++ b/configure.in
@@ -1509,6 +1509,8 @@ fi
 
 AC_CHECK_FUNCS([strtoll strtoq], [break])
 AC_CHECK_FUNCS([strtoull strtouq], [break])
+# strto[u]ll may exist but not be declared
+AC_CHECK_DECLS([strtoll, strtoull])
 
 AC_CACHE_CHECK([for builtin locking functions], pgac_cv_gcc_int_atomics,
 [AC_TRY_LINK([],
diff --git a/src/include/c.h b/src/include/c.h
index 2d1576016ab..6dd2581f11e 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -951,6 +951,14 @@ __attribute__((format(PG_PRINTF_ATTRIBUTE, 3, 4)));
 extern int	vsnprintf(char *str, size_t count, const char *fmt, va_list args);
 #endif
 
+#if defined(HAVE_LONG_LONG_INT) && defined(HAVE_STRTOLL) && !HAVE_DECL_STRTOLL
+extern long long strtoll(const char *str, char **endptr, int base);
+#endif
+
+#if defined(HAVE_LONG_LONG_INT) && defined(HAVE_STRTOULL) && !HAVE_DECL_STRTOULL
+extern unsigned long long strtoull(const char *str, char **endptr, int base);
+#endif
+
 #if !defined(HAVE_MEMMOVE) && !defined(memmove)
 #define memmove(d, s, c)		bcopy(s, d, c)
 #endif
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index c1b7e299b9c..c5885df5435 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -135,6 +135,14 @@
    don't. */
 #undef HAVE_DECL_STRLCPY
 
+/* Define to 1 if you have the declaration of `strtoll', and to 0 if you
+   don't. */
+#undef HAVE_DECL_STRTOLL
+
+/* Define to 1 if you have the declaration of `strtoull', and to 0 if you
+   don't. */
+#undef HAVE_DECL_STRTOULL
+
 /* Define to 1 if you have the declaration of `sys_siglist', and to 0 if you
    don't. */
 #undef HAVE_DECL_SYS_SIGLIST
diff --git a/src/include/pg_config.h.win32 b/src/include/pg_config.h.win32
index 60a5413d208..a678d5a5b05 100644
--- a/src/include/pg_config.h.win32
+++ b/src/include/pg_config.h.win32
@@ -96,6 +96,14 @@
    don't. */
 #define HAVE_DECL_SNPRINTF 1
 
+/* Define to 1 if you have the declaration of `strtoll', and to 0 if you
+   don't. */
+#define HAVE_DECL_STRTOLL 1
+
+/* Define to 1 if you have the declaration of `strtoull', and to 0 if you
+   don't. */
+#define HAVE_DECL_STRTOULL 1
+
 /* Define to 1 if you have the declaration of `vsnprintf', and to 0 if you
    don't. */
 #define HAVE_DECL_VSNPRINTF 1