diff --git a/libstdc++-v3/include/std/format b/libstdc++-v3/include/std/format
index 1afcd042bc2..f4fc85a16d2 100644
--- a/libstdc++-v3/include/std/format
+++ b/libstdc++-v3/include/std/format
@@ -1237,6 +1237,34 @@ namespace __format
   using __float128_t = __ieee128;
 # define _GLIBCXX_FORMAT_F128 1
 
+#ifdef __LONG_DOUBLE_IEEE128__
+  // These overloads exist in the library, but are not declared.
+  // Make them available as std::__format::to_chars.
+  to_chars_result
+  to_chars(char*, char*, __ibm128) noexcept
+    __asm("_ZSt8to_charsPcS_e");
+
+  to_chars_result
+  to_chars(char*, char*, __ibm128, chars_format) noexcept
+    __asm("_ZSt8to_charsPcS_eSt12chars_format");
+
+  to_chars_result
+  to_chars(char*, char*, __ibm128, chars_format, int) noexcept
+    __asm("_ZSt8to_charsPcS_eSt12chars_formati");
+#elif __cplusplus == 202002L
+  to_chars_result
+  to_chars(char*, char*, __ieee128) noexcept
+    __asm("_ZSt8to_charsPcS_u9__ieee128");
+
+  to_chars_result
+  to_chars(char*, char*, __ieee128, chars_format) noexcept
+    __asm("_ZSt8to_charsPcS_u9__ieee128St12chars_format");
+
+  to_chars_result
+  to_chars(char*, char*, __ieee128, chars_format, int) noexcept
+    __asm("_ZSt8to_charsPcS_u9__ieee128St12chars_formati");
+#endif
+
 #elif defined _GLIBCXX_LDOUBLE_IS_IEEE_BINARY128
 
   // Format 128-bit floating-point types using long double.