diff --git a/Objects/stringlib/codecs.h b/Objects/stringlib/codecs.h
index 14fdc6c0832..2eb2d1412ff 100644
--- a/Objects/stringlib/codecs.h
+++ b/Objects/stringlib/codecs.h
@@ -596,110 +596,6 @@ IllegalSurrogate:
 #undef SWAB
 
 
-#if STRINGLIB_MAX_CHAR >= 0x80
-Py_LOCAL_INLINE(Py_ssize_t)
-STRINGLIB(utf16_encode_)(const STRINGLIB_CHAR *in,
-                        Py_ssize_t len,
-                        unsigned short **outptr,
-                        int native_ordering)
-{
-    unsigned short *out = *outptr;
-    const STRINGLIB_CHAR *end = in + len;
-#if STRINGLIB_SIZEOF_CHAR == 1
-# define SWAB2(CH)  ((CH) << 8)
-#else
-# define SWAB2(CH)  (((CH) << 8) | ((CH) >> 8))
-#endif
-    if (native_ordering) {
-#if STRINGLIB_MAX_CHAR < 0x10000
-        const STRINGLIB_CHAR *unrolled_end = in + _Py_SIZE_ROUND_DOWN(len, 4);
-        while (in < unrolled_end) {
-# if STRINGLIB_MAX_CHAR >= 0xd800
-            if (((in[0] ^ 0xd800) &
-                 (in[1] ^ 0xd800) &
-                 (in[2] ^ 0xd800) &
-                 (in[3] ^ 0xd800) & 0xf800) == 0)
-                break;
-# endif
-            out[0] = in[0];
-            out[1] = in[1];
-            out[2] = in[2];
-            out[3] = in[3];
-            in += 4; out += 4;
-        }
-#endif
-        while (in < end) {
-            Py_UCS4 ch;
-            ch = *in++;
-#if STRINGLIB_MAX_CHAR >= 0xd800
-            if (ch < 0xd800)
-                *out++ = ch;
-            else if (ch < 0xe000)
-                /* reject surrogate characters (U+DC800-U+DFFF) */
-                goto fail;
-# if STRINGLIB_MAX_CHAR >= 0x10000
-            else if (ch >= 0x10000) {
-                out[0] = Py_UNICODE_HIGH_SURROGATE(ch);
-                out[1] = Py_UNICODE_LOW_SURROGATE(ch);
-                out += 2;
-            }
-# endif
-            else
-#endif
-                *out++ = ch;
-        }
-    } else {
-#if STRINGLIB_MAX_CHAR < 0x10000
-        const STRINGLIB_CHAR *unrolled_end = in + _Py_SIZE_ROUND_DOWN(len, 4);
-        while (in < unrolled_end) {
-# if STRINGLIB_MAX_CHAR >= 0xd800
-            if (((in[0] ^ 0xd800) &
-                 (in[1] ^ 0xd800) &
-                 (in[2] ^ 0xd800) &
-                 (in[3] ^ 0xd800) & 0xf800) == 0)
-                break;
-# endif
-            out[0] = SWAB2(in[0]);
-            out[1] = SWAB2(in[1]);
-            out[2] = SWAB2(in[2]);
-            out[3] = SWAB2(in[3]);
-            in += 4; out += 4;
-        }
-#endif
-        while (in < end) {
-            Py_UCS4 ch = *in++;
-#if STRINGLIB_MAX_CHAR >= 0xd800
-            if (ch < 0xd800)
-                *out++ = SWAB2((Py_UCS2)ch);
-            else if (ch < 0xe000)
-                /* reject surrogate characters (U+DC800-U+DFFF) */
-                goto fail;
-# if STRINGLIB_MAX_CHAR >= 0x10000
-            else if (ch >= 0x10000) {
-                Py_UCS2 ch1 = Py_UNICODE_HIGH_SURROGATE(ch);
-                Py_UCS2 ch2 = Py_UNICODE_LOW_SURROGATE(ch);
-                out[0] = SWAB2(ch1);
-                out[1] = SWAB2(ch2);
-                out += 2;
-            }
-# endif
-            else
-#endif
-                *out++ = SWAB2((Py_UCS2)ch);
-        }
-    }
-    *outptr = out;
-    return len;
-#if STRINGLIB_MAX_CHAR >= 0xd800
-  fail:
-#endif
-    *outptr = out;
-    return len - (end - in + 1);
-}
-#endif
-
-#undef SWAB2
-
 #if STRINGLIB_MAX_CHAR >= 0x80
 Py_LOCAL_INLINE(Py_ssize_t)
 STRINGLIB(utf16_encode)(const STRINGLIB_CHAR *in,