diff --git a/configure b/configure
index 48440ea3b57..928d7c696dd 100755
--- a/configure
+++ b/configure
@@ -23221,7 +23221,8 @@ fi
 
 
 
-for ac_func in strtoll strtoq
+
+for ac_func in strtoll __strtoll strtoq
 do
 as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 { $as_echo "$as_me:$LINENO: checking for $ac_func" >&5
@@ -23323,7 +23324,8 @@ done
 
 
 
-for ac_func in strtoull strtouq
+
+for ac_func in strtoull __strtoull strtouq
 do
 as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 { $as_echo "$as_me:$LINENO: checking for $ac_func" >&5
diff --git a/configure.in b/configure.in
index 7f11500e4f6..d434dec31ab 100644
--- a/configure.in
+++ b/configure.in
@@ -1507,8 +1507,8 @@ if test x"$pgac_cv_var_int_optreset" = x"yes"; then
   AC_DEFINE(HAVE_INT_OPTRESET, 1, [Define to 1 if you have the global variable 'int optreset'.])
 fi
 
-AC_CHECK_FUNCS([strtoll strtoq], [break])
-AC_CHECK_FUNCS([strtoull strtouq], [break])
+AC_CHECK_FUNCS([strtoll __strtoll strtoq], [break])
+AC_CHECK_FUNCS([strtoull __strtoull strtouq], [break])
 # strto[u]ll may exist but not be declared
 AC_CHECK_DECLS([strtoll, strtoull])
 
diff --git a/src/include/c.h b/src/include/c.h
index 6dd2581f11e..adfb9122a48 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -951,13 +951,40 @@ __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
+#if defined(HAVE_FDATASYNC) && !HAVE_DECL_FDATASYNC
+extern int	fdatasync(int fildes);
+#endif
+
+#ifdef HAVE_LONG_LONG_INT
+/* Older platforms may provide strto[u]ll functionality under other names */
+#if !defined(HAVE_STRTOLL) && defined(HAVE___STRTOLL)
+#define strtoll __strtoll
+#define HAVE_STRTOLL 1
+#endif
+
+#if !defined(HAVE_STRTOLL) && defined(HAVE_STRTOQ)
+#define strtoll strtoq
+#define HAVE_STRTOLL 1
+#endif
+
+#if !defined(HAVE_STRTOULL) && defined(HAVE___STRTOULL)
+#define strtoull __strtoull
+#define HAVE_STRTOULL 1
+#endif
+
+#if !defined(HAVE_STRTOULL) && defined(HAVE_STRTOUQ)
+#define strtoull strtouq
+#define HAVE_STRTOULL 1
+#endif
+
+#if 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
+#if defined(HAVE_STRTOULL) && !HAVE_DECL_STRTOULL
 extern unsigned long long strtoull(const char *str, char **endptr, int base);
 #endif
+#endif							/* HAVE_LONG_LONG_INT */
 
 #if !defined(HAVE_MEMMOVE) && !defined(memmove)
 #define memmove(d, s, c)		bcopy(s, d, c)
@@ -995,22 +1022,6 @@ extern unsigned long long strtoull(const char *str, char **endptr, int base);
 #define siglongjmp longjmp
 #endif
 
-#if defined(HAVE_FDATASYNC) && !HAVE_DECL_FDATASYNC
-extern int	fdatasync(int fildes);
-#endif
-
-/* If strtoq() exists, rename it to the more standard strtoll() */
-#if defined(HAVE_LONG_LONG_INT_64) && !defined(HAVE_STRTOLL) && defined(HAVE_STRTOQ)
-#define strtoll strtoq
-#define HAVE_STRTOLL 1
-#endif
-
-/* If strtouq() exists, rename it to the more standard strtoull() */
-#if defined(HAVE_LONG_LONG_INT_64) && !defined(HAVE_STRTOULL) && defined(HAVE_STRTOUQ)
-#define strtoull strtouq
-#define HAVE_STRTOULL 1
-#endif
-
 /*
  * We assume if we have these two functions, we have their friends too, and
  * can use the wide-character functions.
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index c5885df5435..0121ea80281 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -678,6 +678,12 @@
 /* Define to 1 if your compiler understands __VA_ARGS__ in macros. */
 #undef HAVE__VA_ARGS
 
+/* Define to 1 if you have the `__strtoll' function. */
+#undef HAVE___STRTOLL
+
+/* Define to 1 if you have the `__strtoull' function. */
+#undef HAVE___STRTOULL
+
 /* Define to the appropriate snprintf format for 64-bit ints. */
 #undef INT64_FORMAT
 
diff --git a/src/include/pg_config.h.win32 b/src/include/pg_config.h.win32
index a678d5a5b05..fb58bc505c2 100644
--- a/src/include/pg_config.h.win32
+++ b/src/include/pg_config.h.win32
@@ -391,9 +391,6 @@
 #endif
 #endif
 
-/* Define to 1 if you have the `strtoq' function. */
-/* #undef HAVE_STRTOQ */
-
 /* Define to 1 if you have the `strtoull' function. */
 #ifdef HAVE_LONG_LONG_INT_64
 #define HAVE_STRTOULL 1
@@ -403,9 +400,6 @@
 #endif
 #endif
 
-/* Define to 1 if you have the `strtouq' function. */
-/* #undef HAVE_STRTOUQ */
-
 /* Define to 1 if the system has the type `struct addrinfo'. */
 #if (_MSC_VER > 1200)
 #define HAVE_STRUCT_ADDRINFO 1