diff --git a/libcxx/include/__bit_reference b/libcxx/include/__bit_reference
index 20e5bc7d5695b..00bbc4100ddb9 100644
--- a/libcxx/include/__bit_reference
+++ b/libcxx/include/__bit_reference
@@ -139,7 +139,7 @@ public:
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 operator bool() const _NOEXCEPT {
     return static_cast<bool>(*__seg_ & __mask_);
   }
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool operator~() const _NOEXCEPT {
+  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool operator~() const _NOEXCEPT {
     return !static_cast<bool>(*this);
   }
 
diff --git a/libcxx/include/bitset b/libcxx/include/bitset
index 3453c2fcde71e..271e63b8f5764 100644
--- a/libcxx/include/bitset
+++ b/libcxx/include/bitset
@@ -675,53 +675,62 @@ public:
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset& set(size_t __pos, bool __val = true);
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset& reset() _NOEXCEPT;
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset& reset(size_t __pos);
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset operator~() const _NOEXCEPT;
+  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset operator~() const _NOEXCEPT;
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset& flip() _NOEXCEPT;
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset& flip(size_t __pos);
 
   // element access:
 #  ifdef _LIBCPP_ABI_BITSET_VECTOR_BOOL_CONST_SUBSCRIPT_RETURN_BOOL
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR bool operator[](size_t __p) const {
+  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR bool operator[](size_t __p) const {
     _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__p < _Size, "bitset::operator[] index out of bounds");
     return __base::__make_ref(__p);
   }
 #  else
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __const_reference operator[](size_t __p) const {
+  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __const_reference operator[](size_t __p) const {
     _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__p < _Size, "bitset::operator[] index out of bounds");
     return __base::__make_ref(__p);
   }
 #  endif
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 reference operator[](size_t __p) {
+  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 reference operator[](size_t __p) {
     _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__p < _Size, "bitset::operator[] index out of bounds");
     return __base::__make_ref(__p);
   }
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unsigned long to_ulong() const { return __base::to_ulong(); }
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unsigned long long to_ullong() const {
+  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unsigned long to_ulong() const {
+    return __base::to_ulong();
+  }
+  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unsigned long long to_ullong() const {
     return __base::to_ullong();
   }
   template <class _CharT, class _Traits, class _Allocator>
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 basic_string<_CharT, _Traits, _Allocator>
+  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 basic_string<_CharT, _Traits, _Allocator>
   to_string(_CharT __zero = _CharT('0'), _CharT __one = _CharT('1')) const;
   template <class _CharT, class _Traits>
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 basic_string<_CharT, _Traits, allocator<_CharT> >
+  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI
+  _LIBCPP_CONSTEXPR_SINCE_CXX23 basic_string<_CharT, _Traits, allocator<_CharT> >
   to_string(_CharT __zero = _CharT('0'), _CharT __one = _CharT('1')) const;
   template <class _CharT>
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 basic_string<_CharT, char_traits<_CharT>, allocator<_CharT> >
+  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI
+  _LIBCPP_CONSTEXPR_SINCE_CXX23 basic_string<_CharT, char_traits<_CharT>, allocator<_CharT> >
   to_string(_CharT __zero = _CharT('0'), _CharT __one = _CharT('1')) const;
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 basic_string<char, char_traits<char>, allocator<char> >
+  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI
+  _LIBCPP_CONSTEXPR_SINCE_CXX23 basic_string<char, char_traits<char>, allocator<char> >
   to_string(char __zero = '0', char __one = '1') const;
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 size_t count() const _NOEXCEPT;
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR size_t size() const _NOEXCEPT { return _Size; }
+  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 size_t count() const _NOEXCEPT;
+  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR size_t size() const _NOEXCEPT { return _Size; }
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool operator==(const bitset& __rhs) const _NOEXCEPT;
 #  if _LIBCPP_STD_VER <= 17
   _LIBCPP_HIDE_FROM_ABI bool operator!=(const bitset& __rhs) const _NOEXCEPT;
 #  endif
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool test(size_t __pos) const;
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool all() const _NOEXCEPT { return __base::all(); }
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool any() const _NOEXCEPT { return __base::any(); }
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool none() const _NOEXCEPT { return !any(); }
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset operator<<(size_t __pos) const _NOEXCEPT;
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset operator>>(size_t __pos) const _NOEXCEPT;
+  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool test(size_t __pos) const;
+  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool all() const _NOEXCEPT {
+    return __base::all();
+  }
+  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool any() const _NOEXCEPT {
+    return __base::any();
+  }
+  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool none() const _NOEXCEPT { return !any(); }
+  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset operator<<(size_t __pos) const _NOEXCEPT;
+  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset operator>>(size_t __pos) const _NOEXCEPT;
 
 private:
   template <class _CharT, class _Traits>
@@ -919,7 +928,7 @@ bitset<_Size>::operator>>(size_t __pos) const _NOEXCEPT {
 }
 
 template <size_t _Size>
-inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset<_Size>
+[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset<_Size>
 operator&(const bitset<_Size>& __x, const bitset<_Size>& __y) _NOEXCEPT {
   bitset<_Size> __r = __x;
   __r &= __y;
@@ -927,7 +936,7 @@ operator&(const bitset<_Size>& __x, const bitset<_Size>& __y) _NOEXCEPT {
 }
 
 template <size_t _Size>
-inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset<_Size>
+[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset<_Size>
 operator|(const bitset<_Size>& __x, const bitset<_Size>& __y) _NOEXCEPT {
   bitset<_Size> __r = __x;
   __r |= __y;
@@ -935,7 +944,7 @@ operator|(const bitset<_Size>& __x, const bitset<_Size>& __y) _NOEXCEPT {
 }
 
 template <size_t _Size>
-inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset<_Size>
+[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset<_Size>
 operator^(const bitset<_Size>& __x, const bitset<_Size>& __y) _NOEXCEPT {
   bitset<_Size> __r = __x;
   __r ^= __y;
@@ -944,7 +953,9 @@ operator^(const bitset<_Size>& __x, const bitset<_Size>& __y) _NOEXCEPT {
 
 template <size_t _Size>
 struct hash<bitset<_Size> > : public __unary_function<bitset<_Size>, size_t> {
-  _LIBCPP_HIDE_FROM_ABI size_t operator()(const bitset<_Size>& __bs) const _NOEXCEPT { return __bs.__hash_code(); }
+  [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI size_t operator()(const bitset<_Size>& __bs) const _NOEXCEPT {
+    return __bs.__hash_code();
+  }
 };
 
 template <class _CharT, class _Traits, size_t _Size>
diff --git a/libcxx/test/libcxx/utilities/template.bitset/nodiscard.verify.cpp b/libcxx/test/libcxx/utilities/template.bitset/nodiscard.verify.cpp
new file mode 100644
index 0000000000000..b13fafe2edfc6
--- /dev/null
+++ b/libcxx/test/libcxx/utilities/template.bitset/nodiscard.verify.cpp
@@ -0,0 +1,61 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// <bitset>
+
+// Check that functions are marked [[nodiscard]]
+
+#include <bitset>
+
+#include "test_macros.h"
+#include "test_allocator.h"
+
+void test() {
+  std::bitset<11> bs;
+  const std::bitset<11> cbs;
+
+  // std::bitset<>::reference operator~() const noexcept;
+  ~bs[0]; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  ~bs; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  bs[0];          // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  cbs[0];         // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  bs.to_ulong();  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  bs.to_ullong(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  struct CharTraits : public std::char_traits<char> {};
+
+  // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+  bs.to_string<char, CharTraits, test_allocator<char> >();
+  // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+  bs.to_string<char, CharTraits>();
+#if !defined(TEST_HAS_NO_WIDE_CHARACTERS)
+  // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+  bs.to_string<wchar_t>();
+#endif
+  // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+  bs.to_string();
+
+  bs.count(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  bs.size();  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  bs.test(0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  bs.all();   // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  bs.any();   // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  bs.none();  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  bs << 1;    // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  bs >> 1;    // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  bs & bs; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  bs | bs; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+  bs ^ bs; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  std::hash<std::bitset<11> > hash;
+
+  hash(bs); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+}