diff --git a/libcxx/include/__locale b/libcxx/include/__locale
index fd09206b6c5d5d..23ad424e3c0fc1 100644
--- a/libcxx/include/__locale
+++ b/libcxx/include/__locale
@@ -628,7 +628,7 @@ class _LIBCPP_TYPE_VIS ctype<char>
 public:
     typedef char char_type;
 
-    explicit ctype(const mask* __tab = 0, bool __del = false, size_t __refs = 0);
+    explicit ctype(const mask* __tab = nullptr, bool __del = false, size_t __refs = 0);
 
     _LIBCPP_INLINE_VISIBILITY
     bool is(mask __m, char_type __c) const
diff --git a/libcxx/include/__sso_allocator b/libcxx/include/__sso_allocator
index 117b728f1499a2..c50ae24c92125f 100644
--- a/libcxx/include/__sso_allocator
+++ b/libcxx/include/__sso_allocator
@@ -48,7 +48,7 @@ public:
 private:
     __sso_allocator& operator=(const __sso_allocator&);
 public:
-    _LIBCPP_INLINE_VISIBILITY pointer allocate(size_type __n, typename __sso_allocator<void, _Np>::const_pointer = 0)
+    _LIBCPP_INLINE_VISIBILITY pointer allocate(size_type __n, typename __sso_allocator<void, _Np>::const_pointer = nullptr)
     {
         if (!__allocated_ && __n <= _Np)
         {
diff --git a/libcxx/include/__string b/libcxx/include/__string
index f9d02064401e4a..08be8f1a7641e1 100644
--- a/libcxx/include/__string
+++ b/libcxx/include/__string
@@ -268,7 +268,7 @@ char_traits<_CharT>::find(const char_type* __s, size_t __n, const char_type& __a
             return __s;
         ++__s;
     }
-    return 0;
+    return nullptr;
 }
 
 template <class _CharT>
@@ -683,7 +683,7 @@ char_traits<char8_t>::find(const char_type* __s, size_t __n, const char_type& __
             return __s;
         ++__s;
     }
-    return 0;
+    return nullptr;
 }
 
 #endif // #_LIBCPP_NO_HAS_CHAR8_T
@@ -765,7 +765,7 @@ char_traits<char16_t>::find(const char_type* __s, size_t __n, const char_type& _
             return __s;
         ++__s;
     }
-    return 0;
+    return nullptr;
 }
 
 inline _LIBCPP_CONSTEXPR_AFTER_CXX17
@@ -885,7 +885,7 @@ char_traits<char32_t>::find(const char_type* __s, size_t __n, const char_type& _
             return __s;
         ++__s;
     }
-    return 0;
+    return nullptr;
 }
 
 inline _LIBCPP_CONSTEXPR_AFTER_CXX17
@@ -943,7 +943,7 @@ __str_find(const _CharT *__p, _SizeT __sz,
     if (__pos >= __sz)
         return __npos;
     const _CharT* __r = _Traits::find(__p + __pos, __sz - __pos, __c);
-    if (__r == 0)
+    if (__r == nullptr)
         return __npos;
     return static_cast<_SizeT>(__r - __p);
 }
@@ -972,7 +972,7 @@ __search_substring(const _CharT *__first1, const _CharT *__last1,
 
     // Find __f2 the first byte matching in __first1.
     __first1 = _Traits::find(__first1, __len1 - __len2 + 1, __f2);
-    if (__first1 == 0)
+    if (__first1 == nullptr)
       return __last1;
 
     // It is faster to compare from the first byte of __first1 even if we
@@ -1095,7 +1095,7 @@ __str_find_first_not_of(const _CharT *__p, _SizeT __sz,
     {
         const _CharT* __pe = __p + __sz;
         for (const _CharT* __ps = __p + __pos; __ps != __pe; ++__ps)
-            if (_Traits::find(__s, __n, *__ps) == 0)
+            if (_Traits::find(__s, __n, *__ps) == nullptr)
                 return static_cast<_SizeT>(__ps - __p);
     }
     return __npos;
@@ -1129,7 +1129,7 @@ __str_find_last_not_of(const _CharT *__p, _SizeT __sz,
     else
         __pos = __sz;
     for (const _CharT* __ps = __p + __pos; __ps != __p;)
-        if (_Traits::find(__s, __n, *--__ps) == 0)
+        if (_Traits::find(__s, __n, *--__ps) == nullptr)
             return static_cast<_SizeT>(__ps - __p);
     return __npos;
 }
diff --git a/libcxx/include/__threading_support b/libcxx/include/__threading_support
index 85bb96bdc6baff..2d0ccf5cb2449a 100644
--- a/libcxx/include/__threading_support
+++ b/libcxx/include/__threading_support
@@ -497,13 +497,13 @@ bool __libcpp_thread_id_less(__libcpp_thread_id t1, __libcpp_thread_id t2)
 
 // Thread
 bool __libcpp_thread_isnull(const __libcpp_thread_t *__t) {
-  return *__t == 0;
+  return *__t == __libcpp_thread_t();
 }
 
 int __libcpp_thread_create(__libcpp_thread_t *__t, void *(*__func)(void *),
                            void *__arg)
 {
-  return pthread_create(__t, 0, __func, __arg);
+  return pthread_create(__t, nullptr, __func, __arg);
 }
 
 __libcpp_thread_id __libcpp_thread_get_current_id()
@@ -518,7 +518,7 @@ __libcpp_thread_id __libcpp_thread_get_id(const __libcpp_thread_t *__t)
 
 int __libcpp_thread_join(__libcpp_thread_t *__t)
 {
-  return pthread_join(*__t, 0);
+  return pthread_join(*__t, nullptr);
 }
 
 int __libcpp_thread_detach(__libcpp_thread_t *__t)
diff --git a/libcxx/include/algorithm b/libcxx/include/algorithm
index 4e1afe651acb6d..f047ae1b1dee95 100644
--- a/libcxx/include/algorithm
+++ b/libcxx/include/algorithm
@@ -3405,7 +3405,7 @@ __stable_partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate
         // Update __first to always point to the end of the trues
         value_type* __t = __p.first;
         ::new(__t) value_type(_VSTD::move(*__first));
-        __d.__incr((value_type*)0);
+        __d.template __incr<value_type>();
         ++__t;
         _ForwardIterator __i = __first;
         while (++__i != __last)
@@ -3418,7 +3418,7 @@ __stable_partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate
             else
             {
                 ::new(__t) value_type(_VSTD::move(*__i));
-                __d.__incr((value_type*)0);
+                __d.template __incr<value_type>();
                 ++__t;
             }
         }
@@ -3535,7 +3535,7 @@ __stable_partition(_BidirectionalIterator __first, _BidirectionalIterator __last
         // Update __first to always point to the end of the trues
         value_type* __t = __p.first;
         ::new(__t) value_type(_VSTD::move(*__first));
-        __d.__incr((value_type*)0);
+        __d.template __incr<value_type>();
         ++__t;
         _BidirectionalIterator __i = __first;
         while (++__i != __last)
@@ -3548,7 +3548,7 @@ __stable_partition(_BidirectionalIterator __first, _BidirectionalIterator __last
             else
             {
                 ::new(__t) value_type(_VSTD::move(*__i));
-                __d.__incr((value_type*)0);
+                __d.template __incr<value_type>();
                 ++__t;
             }
         }
@@ -3923,7 +3923,7 @@ __insertion_sort_move(_BirdirectionalIterator __first1, _BirdirectionalIterator
         unique_ptr<value_type, __destruct_n&> __h(__first2, __d);
         value_type* __last2 = __first2;
         ::new(__last2) value_type(_VSTD::move(*__first1));
-        __d.__incr((value_type*)0);
+        __d.template __incr<value_type>();
         for (++__last2; ++__first1 != __last1; ++__last2)
         {
             value_type* __j2 = __last2;
@@ -3931,7 +3931,7 @@ __insertion_sort_move(_BirdirectionalIterator __first1, _BirdirectionalIterator
             if (__comp(*__first1, *--__i2))
             {
                 ::new(__j2) value_type(_VSTD::move(*__i2));
-                __d.__incr((value_type*)0);
+                __d.template __incr<value_type>();
                 for (--__j2; __i2 != __first2 && __comp(*__first1,  *--__i2); --__j2)
                     *__j2 = _VSTD::move(*__i2);
                 *__j2 = _VSTD::move(*__first1);
@@ -3939,7 +3939,7 @@ __insertion_sort_move(_BirdirectionalIterator __first1, _BirdirectionalIterator
             else
             {
                 ::new(__j2) value_type(_VSTD::move(*__first1));
-                __d.__incr((value_type*)0);
+                __d.template __incr<value_type>();
             }
         }
         __h.release();
@@ -4481,14 +4481,14 @@ __buffered_inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator
     if (__len1 <= __len2)
     {
         value_type* __p = __buff;
-        for (_BidirectionalIterator __i = __first; __i != __middle; __d.__incr((value_type*)0), (void) ++__i, (void) ++__p)
+        for (_BidirectionalIterator __i = __first; __i != __middle; __d.template __incr<value_type>(), (void) ++__i, (void) ++__p)
             ::new(__p) value_type(_VSTD::move(*__i));
         __half_inplace_merge(__buff, __p, __middle, __last, __first, __comp);
     }
     else
     {
         value_type* __p = __buff;
-        for (_BidirectionalIterator __i = __middle; __i != __last; __d.__incr((value_type*)0), (void) ++__i, (void) ++__p)
+        for (_BidirectionalIterator __i = __middle; __i != __last; __d.template __incr<value_type>(), (void) ++__i, (void) ++__p)
             ::new(__p) value_type(_VSTD::move(*__i));
         typedef reverse_iterator<_BidirectionalIterator> _RBi;
         typedef reverse_iterator<value_type*> _Rv;
@@ -4628,14 +4628,14 @@ __merge_move_construct(_InputIterator1 __first1, _InputIterator1 __last1,
     {
         if (__first1 == __last1)
         {
-            for (; __first2 != __last2; ++__first2, ++__result, (void) __d.__incr((value_type*)0))
+            for (; __first2 != __last2; ++__first2, ++__result, (void)__d.template __incr<value_type>())
                 ::new (__result) value_type(_VSTD::move(*__first2));
             __h.release();
             return;
         }
         if (__first2 == __last2)
         {
-            for (; __first1 != __last1; ++__first1, ++__result, (void) __d.__incr((value_type*)0))
+            for (; __first1 != __last1; ++__first1, ++__result, (void)__d.template __incr<value_type>())
                 ::new (__result) value_type(_VSTD::move(*__first1));
             __h.release();
             return;
@@ -4643,13 +4643,13 @@ __merge_move_construct(_InputIterator1 __first1, _InputIterator1 __last1,
         if (__comp(*__first2, *__first1))
         {
             ::new (__result) value_type(_VSTD::move(*__first2));
-            __d.__incr((value_type*)0);
+            __d.template __incr<value_type>();
             ++__first2;
         }
         else
         {
             ::new (__result) value_type(_VSTD::move(*__first1));
-            __d.__incr((value_type*)0);
+            __d.template __incr<value_type>();
             ++__first1;
         }
     }
@@ -4710,14 +4710,14 @@ __stable_sort_move(_RandomAccessIterator __first1, _RandomAccessIterator __last1
         if (__comp(*--__last1, *__first1))
         {
             ::new(__first2) value_type(_VSTD::move(*__last1));
-            __d.__incr((value_type*)0);
+            __d.template __incr<value_type>();
             ++__first2;
             ::new(__first2) value_type(_VSTD::move(*__first1));
         }
         else
         {
             ::new(__first2) value_type(_VSTD::move(*__first1));
-            __d.__incr((value_type*)0);
+            __d.template __incr<value_type>();
             ++__first2;
             ::new(__first2) value_type(_VSTD::move(*__last1));
         }
@@ -4772,9 +4772,9 @@ __stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Comp
         __destruct_n __d(0);
         unique_ptr<value_type, __destruct_n&> __h2(__buff, __d);
         __stable_sort_move<_Compare>(__first, __m, __comp, __l2, __buff);
-        __d.__set(__l2, (value_type*)0);
+        __d.__set(__l2, (value_type*)nullptr);
         __stable_sort_move<_Compare>(__m, __last, __comp, __len - __l2, __buff + __l2);
-        __d.__set(__len, (value_type*)0);
+        __d.__set(__len, (value_type*)nullptr);
         __merge_move_assign<_Compare>(__buff, __buff + __l2, __buff + __l2, __buff + __len, __first, __comp);
 //         __merge<_Compare>(move_iterator<value_type*>(__buff),
 //                           move_iterator<value_type*>(__buff + __l2),
diff --git a/libcxx/include/bitset b/libcxx/include/bitset
index 4755fbeb2152cd..0096989eaf43c4 100644
--- a/libcxx/include/bitset
+++ b/libcxx/include/bitset
@@ -625,13 +625,13 @@ protected:
     explicit _LIBCPP_CONSTEXPR __bitset(unsigned long long) _NOEXCEPT;
 
     _LIBCPP_INLINE_VISIBILITY reference __make_ref(size_t) _NOEXCEPT
-        {return reference(0, 1);}
+        {return reference(nullptr, 1);}
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR const_reference __make_ref(size_t) const _NOEXCEPT
-        {return const_reference(0, 1);}
+        {return const_reference(nullptr, 1);}
     _LIBCPP_INLINE_VISIBILITY iterator __make_iter(size_t) _NOEXCEPT
-        {return iterator(0, 0);}
+        {return iterator(nullptr, 0);}
     _LIBCPP_INLINE_VISIBILITY const_iterator __make_iter(size_t) const _NOEXCEPT
-        {return const_iterator(0, 0);}
+        {return const_iterator(nullptr, 0);}
 
     _LIBCPP_INLINE_VISIBILITY void operator&=(const __bitset&) _NOEXCEPT {}
     _LIBCPP_INLINE_VISIBILITY void operator|=(const __bitset&) _NOEXCEPT {}
diff --git a/libcxx/include/chrono b/libcxx/include/chrono
index 7b53a0d489656a..53e4546010cd8b 100644
--- a/libcxx/include/chrono
+++ b/libcxx/include/chrono
@@ -1077,7 +1077,7 @@ public:
                is_convertible<_Rep2, rep>::value &&
                (treat_as_floating_point<rep>::value ||
                !treat_as_floating_point<_Rep2>::value)
-            >::type* = 0)
+            >::type* = nullptr)
                 : __rep_(__r) {}
 
     // conversions
@@ -1090,7 +1090,7 @@ public:
                 treat_as_floating_point<rep>::value ||
                 (__no_overflow<_Period2, period>::type::den == 1 &&
                  !treat_as_floating_point<_Rep2>::value))
-            >::type* = 0)
+            >::type* = nullptr)
                 : __rep_(_VSTD::chrono::duration_cast<duration>(__d).count()) {}
 
     // observer
@@ -1376,7 +1376,7 @@ public:
         typename enable_if
         <
             is_convertible<_Duration2, duration>::value
-        >::type* = 0)
+        >::type* = nullptr)
             : __d_(t.time_since_epoch()) {}
 
     // observer
diff --git a/libcxx/include/fstream b/libcxx/include/fstream
index 1e2d6072e8fede..af8476c6d451bf 100644
--- a/libcxx/include/fstream
+++ b/libcxx/include/fstream
@@ -287,13 +287,13 @@ private:
 
 template <class _CharT, class _Traits>
 basic_filebuf<_CharT, _Traits>::basic_filebuf()
-    : __extbuf_(0),
-      __extbufnext_(0),
-      __extbufend_(0),
+    : __extbuf_(nullptr),
+      __extbufnext_(nullptr),
+      __extbufend_(nullptr),
       __ebs_(0),
-      __intbuf_(0),
+      __intbuf_(nullptr),
       __ibs_(0),
-      __file_(0),
+      __file_(nullptr),
       __cv_(nullptr),
       __st_(),
       __st_last_(),
@@ -308,7 +308,7 @@ basic_filebuf<_CharT, _Traits>::basic_filebuf()
         __cv_ = &use_facet<codecvt<char_type, char, state_type> >(this->getloc());
         __always_noconv_ = __cv_->always_noconv();
     }
-    setbuf(0, 4096);
+    setbuf(nullptr, 4096);
 }
 
 #ifndef _LIBCPP_CXX03_LANG
@@ -360,13 +360,13 @@ basic_filebuf<_CharT, _Traits>::basic_filebuf(basic_filebuf&& __rhs)
                        (char_type*)__extbuf_ + (__rhs.gptr() - __rhs.eback()),
                        (char_type*)__extbuf_ + (__rhs.egptr() - __rhs.eback()));
     }
-    __rhs.__extbuf_ = 0;
-    __rhs.__extbufnext_ = 0;
-    __rhs.__extbufend_ = 0;
+    __rhs.__extbuf_ = nullptr;
+    __rhs.__extbufnext_ = nullptr;
+    __rhs.__extbufend_ = nullptr;
     __rhs.__ebs_ = 0;
     __rhs.__intbuf_ = 0;
     __rhs.__ibs_ = 0;
-    __rhs.__file_ = 0;
+    __rhs.__file_ = nullptr;
     __rhs.__st_ = state_type();
     __rhs.__st_last_ = state_type();
     __rhs.__om_ = 0;
@@ -500,7 +500,7 @@ inline
 bool
 basic_filebuf<_CharT, _Traits>::is_open() const
 {
-    return __file_ != 0;
+    return __file_ != nullptr;
 }
 
 template <class _CharT, class _Traits>
@@ -548,8 +548,8 @@ template <class _CharT, class _Traits>
 basic_filebuf<_CharT, _Traits>*
 basic_filebuf<_CharT, _Traits>::open(const char* __s, ios_base::openmode __mode)
 {
-    basic_filebuf<_CharT, _Traits>* __rt = 0;
-    if (__file_ == 0)
+    basic_filebuf<_CharT, _Traits>* __rt = nullptr;
+    if (__file_ == nullptr)
     {
       if (const char* __mdstr = __make_mdstring(__mode)) {
         __rt = this;
@@ -559,12 +559,12 @@ basic_filebuf<_CharT, _Traits>::open(const char* __s, ios_base::openmode __mode)
           if (__mode & ios_base::ate) {
             if (fseek(__file_, 0, SEEK_END)) {
               fclose(__file_);
-              __file_ = 0;
-              __rt = 0;
+              __file_ = nullptr;
+              __rt = nullptr;
             }
           }
         } else
-          __rt = 0;
+          __rt = nullptr;
       }
     }
     return __rt;
@@ -574,8 +574,8 @@ template <class _CharT, class _Traits>
 inline _LIBCPP_INLINE_VISIBILITY
 basic_filebuf<_CharT, _Traits>*
 basic_filebuf<_CharT, _Traits>::__open(int __fd, ios_base::openmode __mode) {
-  basic_filebuf<_CharT, _Traits>* __rt = 0;
-  if (__file_ == 0) {
+  basic_filebuf<_CharT, _Traits>* __rt = nullptr;
+  if (__file_ == nullptr) {
     if (const char* __mdstr = __make_mdstring(__mode)) {
       __rt = this;
       __file_ = fdopen(__fd, __mdstr);
@@ -584,12 +584,12 @@ basic_filebuf<_CharT, _Traits>::__open(int __fd, ios_base::openmode __mode) {
         if (__mode & ios_base::ate) {
           if (fseek(__file_, 0, SEEK_END)) {
             fclose(__file_);
-            __file_ = 0;
-            __rt = 0;
+            __file_ = nullptr;
+            __rt = nullptr;
           }
         }
       } else
-        __rt = 0;
+        __rt = nullptr;
     }
   }
   return __rt;
@@ -602,8 +602,8 @@ template <class _CharT, class _Traits>
 basic_filebuf<_CharT, _Traits>*
 basic_filebuf<_CharT, _Traits>::open(const wchar_t* __s, ios_base::openmode __mode)
 {
-    basic_filebuf<_CharT, _Traits>* __rt = 0;
-    if (__file_ == 0)
+    basic_filebuf<_CharT, _Traits>* __rt = nullptr;
+    if (__file_ == nullptr)
     {
         __rt = this;
         const wchar_t* __mdstr;
@@ -652,7 +652,7 @@ basic_filebuf<_CharT, _Traits>::open(const wchar_t* __s, ios_base::openmode __mo
             __mdstr = L"a+b";
             break;
         default:
-            __rt = 0;
+            __rt = nullptr;
             break;
         }
         if (__rt)
@@ -666,13 +666,13 @@ basic_filebuf<_CharT, _Traits>::open(const wchar_t* __s, ios_base::openmode __mo
                     if (fseek(__file_, 0, SEEK_END))
                     {
                         fclose(__file_);
-                        __file_ = 0;
-                        __rt = 0;
+                        __file_ = nullptr;
+                        __rt = nullptr;
                     }
                 }
             }
             else
-                __rt = 0;
+                __rt = nullptr;
         }
     }
     return __rt;
@@ -692,16 +692,16 @@ template <class _CharT, class _Traits>
 basic_filebuf<_CharT, _Traits>*
 basic_filebuf<_CharT, _Traits>::close()
 {
-    basic_filebuf<_CharT, _Traits>* __rt = 0;
+    basic_filebuf<_CharT, _Traits>* __rt = nullptr;
     if (__file_)
     {
         __rt = this;
         unique_ptr<FILE, int(*)(FILE*)> __h(__file_, fclose);
         if (sync())
-            __rt = 0;
+            __rt = nullptr;
         if (fclose(__h.release()))
-            __rt = 0;
-        __file_ = 0;
+            __rt = nullptr;
+        __file_ = nullptr;
         setbuf(0, 0);
     }
     return __rt;
@@ -711,11 +711,11 @@ template <class _CharT, class _Traits>
 typename basic_filebuf<_CharT, _Traits>::int_type
 basic_filebuf<_CharT, _Traits>::underflow()
 {
-    if (__file_ == 0)
+    if (__file_ == nullptr)
         return traits_type::eof();
     bool __initial = __read_mode();
     char_type __1buf;
-    if (this->gptr() == 0)
+    if (this->gptr() == nullptr)
         this->setg(&__1buf, &__1buf+1, &__1buf+1);
     const size_t __unget_sz = __initial ? 0 : min<size_t>((this->egptr() - this->eback()) / 2, 4);
     int_type __c = traits_type::eof();
@@ -773,7 +773,7 @@ basic_filebuf<_CharT, _Traits>::underflow()
     else
         __c = traits_type::to_int_type(*this->gptr());
     if (this->eback() == &__1buf)
-        this->setg(0, 0, 0);
+        this->setg(nullptr, nullptr, nullptr);
     return __c;
 }
 
@@ -803,7 +803,7 @@ template <class _CharT, class _Traits>
 typename basic_filebuf<_CharT, _Traits>::int_type
 basic_filebuf<_CharT, _Traits>::overflow(int_type __c)
 {
-    if (__file_ == 0)
+    if (__file_ == nullptr)
         return traits_type::eof();
     __write_mode();
     char_type __1buf;
@@ -811,7 +811,7 @@ basic_filebuf<_CharT, _Traits>::overflow(int_type __c)
     char_type* __epb_save = this->epptr();
     if (!traits_type::eq_int_type(__c, traits_type::eof()))
     {
-        if (this->pptr() == 0)
+        if (this->pptr() == nullptr)
             this->setp(&__1buf, &__1buf+1);
         *this->pptr() = traits_type::to_char_type(__c);
         this->pbump(1);
@@ -868,8 +868,8 @@ template <class _CharT, class _Traits>
 basic_streambuf<_CharT, _Traits>*
 basic_filebuf<_CharT, _Traits>::setbuf(char_type* __s, streamsize __n)
 {
-    this->setg(0, 0, 0);
-    this->setp(0, 0);
+    this->setg(nullptr, nullptr, nullptr);
+    this->setp(nullptr, nullptr);
     if (__owns_eb_)
         delete [] __extbuf_;
     if (__owns_ib_)
@@ -911,7 +911,7 @@ basic_filebuf<_CharT, _Traits>::setbuf(char_type* __s, streamsize __n)
     else
     {
         __ibs_ = 0;
-        __intbuf_ = 0;
+        __intbuf_ = nullptr;
         __owns_ib_ = false;
     }
     return this;
@@ -926,7 +926,7 @@ basic_filebuf<_CharT, _Traits>::seekoff(off_type __off, ios_base::seekdir __way,
         __throw_bad_cast();
 
     int __width = __cv_->encoding();
-    if (__file_ == 0 || (__width <= 0 && __off != 0) || sync())
+    if (__file_ == nullptr || (__width <= 0 && __off != 0) || sync())
         return pos_type(off_type(-1));
     // __width > 0 || __off == 0
     int __whence;
@@ -961,7 +961,7 @@ template <class _CharT, class _Traits>
 typename basic_filebuf<_CharT, _Traits>::pos_type
 basic_filebuf<_CharT, _Traits>::seekpos(pos_type __sp, ios_base::openmode)
 {
-    if (__file_ == 0 || sync())
+    if (__file_ == nullptr || sync())
         return pos_type(off_type(-1));
 #if defined(_LIBCPP_HAS_NO_OFF_T_FUNCTIONS)
     if (fseek(__file_, __sp, SEEK_SET))
@@ -978,7 +978,7 @@ template <class _CharT, class _Traits>
 int
 basic_filebuf<_CharT, _Traits>::sync()
 {
-    if (__file_ == 0)
+    if (__file_ == nullptr)
         return 0;
     if (!__cv_)
         __throw_bad_cast();
@@ -1037,7 +1037,7 @@ basic_filebuf<_CharT, _Traits>::sync()
         if (__update_st)
             __st_ = __state;
         __extbufnext_ = __extbufend_ = __extbuf_;
-        this->setg(0, 0, 0);
+        this->setg(nullptr, nullptr, nullptr);
         __cm_ = 0;
     }
     return 0;
@@ -1053,8 +1053,8 @@ basic_filebuf<_CharT, _Traits>::imbue(const locale& __loc)
     __always_noconv_ = __cv_->always_noconv();
     if (__old_anc != __always_noconv_)
     {
-        this->setg(0, 0, 0);
-        this->setp(0, 0);
+        this->setg(nullptr, nullptr, nullptr);
+        this->setp(nullptr, nullptr);
         // invariant, char_type is char, else we couldn't get here
         if (__always_noconv_)  // need to dump __intbuf_
         {
@@ -1064,7 +1064,7 @@ basic_filebuf<_CharT, _Traits>::imbue(const locale& __loc)
             __ebs_ = __ibs_;
             __extbuf_ = (char*)__intbuf_;
             __ibs_ = 0;
-            __intbuf_ = 0;
+            __intbuf_ = nullptr;
             __owns_ib_ = false;
         }
         else  // need to obtain an __intbuf_.
@@ -1093,7 +1093,7 @@ basic_filebuf<_CharT, _Traits>::__read_mode()
 {
     if (!(__cm_ & ios_base::in))
     {
-        this->setp(0, 0);
+        this->setp(nullptr, nullptr);
         if (__always_noconv_)
             this->setg((char_type*)__extbuf_,
                        (char_type*)__extbuf_ + __ebs_,
@@ -1112,7 +1112,7 @@ basic_filebuf<_CharT, _Traits>::__write_mode()
 {
     if (!(__cm_ & ios_base::out))
     {
-        this->setg(0, 0, 0);
+        this->setg(nullptr, nullptr, nullptr);
         if (__ebs_ > sizeof(__extbuf_min_))
         {
             if (__always_noconv_)
@@ -1122,7 +1122,7 @@ basic_filebuf<_CharT, _Traits>::__write_mode()
                 this->setp(__intbuf_, __intbuf_ + (__ibs_ - 1));
         }
         else
-            this->setp(0, 0);
+            this->setp(nullptr, nullptr);
         __cm_ = ios_base::out;
     }
 }
@@ -1208,7 +1208,7 @@ inline
 basic_ifstream<_CharT, _Traits>::basic_ifstream(const char* __s, ios_base::openmode __mode)
     : basic_istream<char_type, traits_type>(&__sb_)
 {
-    if (__sb_.open(__s, __mode | ios_base::in) == 0)
+    if (__sb_.open(__s, __mode | ios_base::in) == nullptr)
         this->setstate(ios_base::failbit);
 }
 
@@ -1218,7 +1218,7 @@ inline
 basic_ifstream<_CharT, _Traits>::basic_ifstream(const wchar_t* __s, ios_base::openmode __mode)
     : basic_istream<char_type, traits_type>(&__sb_)
 {
-    if (__sb_.open(__s, __mode | ios_base::in) == 0)
+    if (__sb_.open(__s, __mode | ios_base::in) == nullptr)
         this->setstate(ios_base::failbit);
 }
 #endif
@@ -1228,7 +1228,7 @@ inline
 basic_ifstream<_CharT, _Traits>::basic_ifstream(const string& __s, ios_base::openmode __mode)
     : basic_istream<char_type, traits_type>(&__sb_)
 {
-    if (__sb_.open(__s, __mode | ios_base::in) == 0)
+    if (__sb_.open(__s, __mode | ios_base::in) == nullptr)
         this->setstate(ios_base::failbit);
 }
 #endif
@@ -1421,7 +1421,7 @@ inline
 basic_ofstream<_CharT, _Traits>::basic_ofstream(const char* __s, ios_base::openmode __mode)
     : basic_ostream<char_type, traits_type>(&__sb_)
 {
-    if (__sb_.open(__s, __mode | ios_base::out) == 0)
+    if (__sb_.open(__s, __mode | ios_base::out) == nullptr)
         this->setstate(ios_base::failbit);
 }
 
@@ -1431,7 +1431,7 @@ inline
 basic_ofstream<_CharT, _Traits>::basic_ofstream(const wchar_t* __s, ios_base::openmode __mode)
     : basic_ostream<char_type, traits_type>(&__sb_)
 {
-    if (__sb_.open(__s, __mode | ios_base::out) == 0)
+    if (__sb_.open(__s, __mode | ios_base::out) == nullptr)
         this->setstate(ios_base::failbit);
 }
 #endif
@@ -1441,7 +1441,7 @@ inline
 basic_ofstream<_CharT, _Traits>::basic_ofstream(const string& __s, ios_base::openmode __mode)
     : basic_ostream<char_type, traits_type>(&__sb_)
 {
-    if (__sb_.open(__s, __mode | ios_base::out) == 0)
+    if (__sb_.open(__s, __mode | ios_base::out) == nullptr)
         this->setstate(ios_base::failbit);
 }
 #endif
@@ -1550,7 +1550,7 @@ inline
 void
 basic_ofstream<_CharT, _Traits>::close()
 {
-    if (__sb_.close() == 0)
+    if (__sb_.close() == nullptr)
         this->setstate(ios_base::failbit);
 }
 
@@ -1634,7 +1634,7 @@ inline
 basic_fstream<_CharT, _Traits>::basic_fstream(const char* __s, ios_base::openmode __mode)
     : basic_iostream<char_type, traits_type>(&__sb_)
 {
-    if (__sb_.open(__s, __mode) == 0)
+    if (__sb_.open(__s, __mode) == nullptr)
         this->setstate(ios_base::failbit);
 }
 
@@ -1644,7 +1644,7 @@ inline
 basic_fstream<_CharT, _Traits>::basic_fstream(const wchar_t* __s, ios_base::openmode __mode)
     : basic_iostream<char_type, traits_type>(&__sb_)
 {
-    if (__sb_.open(__s, __mode) == 0)
+    if (__sb_.open(__s, __mode) == nullptr)
         this->setstate(ios_base::failbit);
 }
 #endif
@@ -1654,7 +1654,7 @@ inline
 basic_fstream<_CharT, _Traits>::basic_fstream(const string& __s, ios_base::openmode __mode)
     : basic_iostream<char_type, traits_type>(&__sb_)
 {
-    if (__sb_.open(__s, __mode) == 0)
+    if (__sb_.open(__s, __mode) == nullptr)
         this->setstate(ios_base::failbit);
 }
 #endif
@@ -1754,7 +1754,7 @@ inline
 void
 basic_fstream<_CharT, _Traits>::close()
 {
-    if (__sb_.close() == 0)
+    if (__sb_.close() == nullptr)
         this->setstate(ios_base::failbit);
 }
 
diff --git a/libcxx/include/functional b/libcxx/include/functional
index 9a0ca96c4611be..0979e7d2bd1d71 100644
--- a/libcxx/include/functional
+++ b/libcxx/include/functional
@@ -1735,7 +1735,7 @@ __func<_Fp, _Alloc, _Rp(_ArgTypes...)>::target(const type_info& __ti) const _NOE
 {
     if (__ti == typeid(_Fp))
         return &__f_.__target();
-    return (const void*)0;
+    return nullptr;
 }
 
 template<class _Fp, class _Alloc, class _Rp, class ..._ArgTypes>
@@ -1765,11 +1765,11 @@ template <class _Rp, class... _ArgTypes> class __value_func<_Rp(_ArgTypes...)>
 
   public:
     _LIBCPP_INLINE_VISIBILITY
-    __value_func() _NOEXCEPT : __f_(0) {}
+    __value_func() _NOEXCEPT : __f_(nullptr) {}
 
     template <class _Fp, class _Alloc>
     _LIBCPP_INLINE_VISIBILITY __value_func(_Fp&& __f, const _Alloc& __a)
-        : __f_(0)
+        : __f_(nullptr)
     {
         typedef allocator_traits<_Alloc> __alloc_traits;
         typedef __function::__func<_Fp, _Alloc, _Rp(_ArgTypes...)> _Fun;
@@ -1804,8 +1804,8 @@ template <class _Rp, class... _ArgTypes> class __value_func<_Rp(_ArgTypes...)>
     _LIBCPP_INLINE_VISIBILITY
     __value_func(const __value_func& __f)
     {
-        if (__f.__f_ == 0)
-            __f_ = 0;
+        if (__f.__f_ == nullptr)
+            __f_ = nullptr;
         else if ((void*)__f.__f_ == &__f.__buf_)
         {
             __f_ = __as_base(&__buf_);
@@ -1818,8 +1818,8 @@ template <class _Rp, class... _ArgTypes> class __value_func<_Rp(_ArgTypes...)>
     _LIBCPP_INLINE_VISIBILITY
     __value_func(__value_func&& __f) _NOEXCEPT
     {
-        if (__f.__f_ == 0)
-            __f_ = 0;
+        if (__f.__f_ == nullptr)
+            __f_ = nullptr;
         else if ((void*)__f.__f_ == &__f.__buf_)
         {
             __f_ = __as_base(&__buf_);
@@ -1828,7 +1828,7 @@ template <class _Rp, class... _ArgTypes> class __value_func<_Rp(_ArgTypes...)>
         else
         {
             __f_ = __f.__f_;
-            __f.__f_ = 0;
+            __f.__f_ = nullptr;
         }
     }
 
@@ -1845,8 +1845,8 @@ template <class _Rp, class... _ArgTypes> class __value_func<_Rp(_ArgTypes...)>
     __value_func& operator=(__value_func&& __f)
     {
         *this = nullptr;
-        if (__f.__f_ == 0)
-            __f_ = 0;
+        if (__f.__f_ == nullptr)
+            __f_ = nullptr;
         else if ((void*)__f.__f_ == &__f.__buf_)
         {
             __f_ = __as_base(&__buf_);
@@ -1855,7 +1855,7 @@ template <class _Rp, class... _ArgTypes> class __value_func<_Rp(_ArgTypes...)>
         else
         {
             __f_ = __f.__f_;
-            __f.__f_ = 0;
+            __f.__f_ = nullptr;
         }
         return *this;
     }
@@ -1864,7 +1864,7 @@ template <class _Rp, class... _ArgTypes> class __value_func<_Rp(_ArgTypes...)>
     __value_func& operator=(nullptr_t)
     {
         __func* __f = __f_;
-        __f_ = 0;
+        __f_ = nullptr;
         if ((void*)__f == &__buf_)
             __f->destroy();
         else if (__f)
@@ -1875,7 +1875,7 @@ template <class _Rp, class... _ArgTypes> class __value_func<_Rp(_ArgTypes...)>
     _LIBCPP_INLINE_VISIBILITY
     _Rp operator()(_ArgTypes&&... __args) const
     {
-        if (__f_ == 0)
+        if (__f_ == nullptr)
             __throw_bad_function_call();
         return (*__f_)(_VSTD::forward<_ArgTypes>(__args)...);
     }
@@ -1891,10 +1891,10 @@ template <class _Rp, class... _ArgTypes> class __value_func<_Rp(_ArgTypes...)>
             __func* __t = __as_base(&__tempbuf);
             __f_->__clone(__t);
             __f_->destroy();
-            __f_ = 0;
+            __f_ = nullptr;
             __f.__f_->__clone(__as_base(&__buf_));
             __f.__f_->destroy();
-            __f.__f_ = 0;
+            __f.__f_ = nullptr;
             __f_ = __as_base(&__buf_);
             __t->__clone(__as_base(&__f.__buf_));
             __t->destroy();
@@ -1919,13 +1919,13 @@ template <class _Rp, class... _ArgTypes> class __value_func<_Rp(_ArgTypes...)>
     }
 
     _LIBCPP_INLINE_VISIBILITY
-    _LIBCPP_EXPLICIT operator bool() const _NOEXCEPT { return __f_ != 0; }
+    _LIBCPP_EXPLICIT operator bool() const _NOEXCEPT { return __f_ != nullptr; }
 
 #ifndef _LIBCPP_NO_RTTI
     _LIBCPP_INLINE_VISIBILITY
     const std::type_info& target_type() const _NOEXCEPT
     {
-        if (__f_ == 0)
+        if (__f_ == nullptr)
             return typeid(void);
         return __f_->target_type();
     }
@@ -1933,8 +1933,8 @@ template <class _Rp, class... _ArgTypes> class __value_func<_Rp(_ArgTypes...)>
     template <typename _Tp>
     _LIBCPP_INLINE_VISIBILITY const _Tp* target() const _NOEXCEPT
     {
-        if (__f_ == 0)
-            return 0;
+        if (__f_ == nullptr)
+            return nullptr;
         return (const _Tp*)__f_->target(typeid(_Tp));
     }
 #endif // _LIBCPP_NO_RTTI
diff --git a/libcxx/include/ios b/libcxx/include/ios
index ae758ddb35ef74..653e3a95fc7eeb 100644
--- a/libcxx/include/ios
+++ b/libcxx/include/ios
@@ -710,7 +710,7 @@ void
 basic_ios<_CharT, _Traits>::init(basic_streambuf<char_type, traits_type>* __sb)
 {
     ios_base::init(__sb);
-    __tie_ = 0;
+    __tie_ = nullptr;
     __fill_ = traits_type::eof();
 }
 
@@ -821,7 +821,7 @@ basic_ios<_CharT, _Traits>::move(basic_ios& __rhs)
 {
     ios_base::move(__rhs);
     __tie_ = __rhs.__tie_;
-    __rhs.__tie_ = 0;
+    __rhs.__tie_ = nullptr;
     __fill_ = __rhs.__fill_;
 }
 
diff --git a/libcxx/include/istream b/libcxx/include/istream
index c541905b2ea230..5e984909f87832 100644
--- a/libcxx/include/istream
+++ b/libcxx/include/istream
@@ -1142,7 +1142,7 @@ basic_istream<_CharT, _Traits>::putback(char_type __c)
         try
         {
 #endif  // _LIBCPP_NO_EXCEPTIONS
-            if (this->rdbuf() == 0 || this->rdbuf()->sputbackc(__c) == traits_type::eof())
+            if (this->rdbuf() == nullptr || this->rdbuf()->sputbackc(__c) == traits_type::eof())
                 __state |= ios_base::badbit;
 #ifndef _LIBCPP_NO_EXCEPTIONS
         }
@@ -1179,7 +1179,7 @@ basic_istream<_CharT, _Traits>::unget()
         try
         {
 #endif  // _LIBCPP_NO_EXCEPTIONS
-            if (this->rdbuf() == 0 || this->rdbuf()->sungetc() == traits_type::eof())
+            if (this->rdbuf() == nullptr || this->rdbuf()->sungetc() == traits_type::eof())
                 __state |= ios_base::badbit;
 #ifndef _LIBCPP_NO_EXCEPTIONS
         }
@@ -1215,7 +1215,7 @@ basic_istream<_CharT, _Traits>::sync()
         try
         {
 #endif  // _LIBCPP_NO_EXCEPTIONS
-            if (this->rdbuf() == 0)
+            if (this->rdbuf() == nullptr)
                 return -1;
             if (this->rdbuf()->pubsync() == -1)
             {
diff --git a/libcxx/include/iterator b/libcxx/include/iterator
index 99f9b8173dbfe3..d4667d39ddb885 100644
--- a/libcxx/include/iterator
+++ b/libcxx/include/iterator
@@ -512,9 +512,9 @@ struct __has_iterator_category
 private:
     struct __two {char __lx; char __lxx;};
     template <class _Up> static __two __test(...);
-    template <class _Up> static char __test(typename _Up::iterator_category* = 0);
+    template <class _Up> static char __test(typename _Up::iterator_category* = nullptr);
 public:
-    static const bool value = sizeof(__test<_Tp>(0)) == 1;
+    static const bool value = sizeof(__test<_Tp>(nullptr)) == 1;
 };
 
 template <class _Iter, bool> struct __iterator_traits_impl {};
@@ -995,11 +995,11 @@ private:
     istream_type* __in_stream_;
     _Tp __value_;
 public:
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR istream_iterator() : __in_stream_(0), __value_() {}
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR istream_iterator() : __in_stream_(nullptr), __value_() {}
     _LIBCPP_INLINE_VISIBILITY istream_iterator(istream_type& __s) : __in_stream_(_VSTD::addressof(__s))
         {
             if (!(*__in_stream_ >> __value_))
-                __in_stream_ = 0;
+                __in_stream_ = nullptr;
         }
 
     _LIBCPP_INLINE_VISIBILITY const _Tp& operator*() const {return __value_;}
@@ -1007,7 +1007,7 @@ public:
     _LIBCPP_INLINE_VISIBILITY istream_iterator& operator++()
         {
             if (!(*__in_stream_ >> __value_))
-                __in_stream_ = 0;
+                __in_stream_ = nullptr;
             return *this;
         }
     _LIBCPP_INLINE_VISIBILITY istream_iterator  operator++(int)
@@ -1067,7 +1067,7 @@ private:
     const char_type* __delim_;
 public:
     _LIBCPP_INLINE_VISIBILITY ostream_iterator(ostream_type& __s) _NOEXCEPT
-        : __out_stream_(_VSTD::addressof(__s)), __delim_(0) {}
+        : __out_stream_(_VSTD::addressof(__s)), __delim_(nullptr) {}
     _LIBCPP_INLINE_VISIBILITY ostream_iterator(ostream_type& __s, const _CharT* __delimiter) _NOEXCEPT
         : __out_stream_(_VSTD::addressof(__s)), __delim_(__delimiter) {}
     _LIBCPP_INLINE_VISIBILITY ostream_iterator& operator=(const _Tp& __value_)
@@ -1113,11 +1113,11 @@ private:
     bool __test_for_eof() const
     {
         if (__sbuf_ && traits_type::eq_int_type(__sbuf_->sgetc(), traits_type::eof()))
-            __sbuf_ = 0;
-        return __sbuf_ == 0;
+            __sbuf_ = nullptr;
+        return __sbuf_ == nullptr;
     }
 public:
-    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR istreambuf_iterator() _NOEXCEPT : __sbuf_(0) {}
+    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR istreambuf_iterator() _NOEXCEPT : __sbuf_(nullptr) {}
     _LIBCPP_INLINE_VISIBILITY istreambuf_iterator(istream_type& __s) _NOEXCEPT
         : __sbuf_(__s.rdbuf()) {}
     _LIBCPP_INLINE_VISIBILITY istreambuf_iterator(streambuf_type* __s) _NOEXCEPT
@@ -1182,13 +1182,13 @@ public:
     _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator=(_CharT __c)
         {
             if (__sbuf_ && traits_type::eq_int_type(__sbuf_->sputc(__c), traits_type::eof()))
-                __sbuf_ = 0;
+                __sbuf_ = nullptr;
             return *this;
         }
     _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator*()     {return *this;}
     _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator++()    {return *this;}
     _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator++(int) {return *this;}
-    _LIBCPP_INLINE_VISIBILITY bool failed() const _NOEXCEPT {return __sbuf_ == 0;}
+    _LIBCPP_INLINE_VISIBILITY bool failed() const _NOEXCEPT {return __sbuf_ == nullptr;}
 
     template <class _Ch, class _Tr>
     friend
@@ -1441,7 +1441,7 @@ public:
     }
     template <class _Up> _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
         __wrap_iter(const __wrap_iter<_Up>& __u,
-            typename enable_if<is_convertible<_Up, iterator_type>::value>::type* = 0) _NOEXCEPT
+            typename enable_if<is_convertible<_Up, iterator_type>::value>::type* = nullptr) _NOEXCEPT
             : __i(__u.base())
     {
 #if _LIBCPP_DEBUG_LEVEL == 2
diff --git a/libcxx/include/locale b/libcxx/include/locale
index 2723c0cfea6662..80a5134fdb2e6a 100644
--- a/libcxx/include/locale
+++ b/libcxx/include/locale
@@ -257,11 +257,11 @@ __scan_keyword(_InputIterator& __b, _InputIterator __e,
     const unsigned char __does_match = '\2';
     unsigned char __statbuf[100];
     unsigned char* __status = __statbuf;
-    unique_ptr<unsigned char, void(*)(void*)> __stat_hold(0, free);
+    unique_ptr<unsigned char, void(*)(void*)> __stat_hold(nullptr, free);
     if (__nkw > sizeof(__statbuf))
     {
         __status = (unsigned char*)malloc(__nkw);
-        if (__status == 0)
+        if (__status == nullptr)
             __throw_bad_alloc();
         __stat_hold.reset(__status);
     }
@@ -1560,14 +1560,14 @@ num_put<_CharT, _OutputIterator>::do_put(iter_type __s, ios_base& __iob,
                                    (int)__iob.precision(), __v);
     else
         __nc = __libcpp_snprintf_l(__nb, __nbuf, _LIBCPP_GET_C_LOCALE, __fmt, __v);
-    unique_ptr<char, void(*)(void*)> __nbh(0, free);
+    unique_ptr<char, void(*)(void*)> __nbh(nullptr, free);
     if (__nc > static_cast<int>(__nbuf-1))
     {
         if (__specify_precision)
             __nc = __libcpp_asprintf_l(&__nb, _LIBCPP_GET_C_LOCALE, __fmt, (int)__iob.precision(), __v);
         else
             __nc = __libcpp_asprintf_l(&__nb, _LIBCPP_GET_C_LOCALE, __fmt, __v);
-        if (__nb == 0)
+        if (__nb == nullptr)
             __throw_bad_alloc();
         __nbh.reset(__nb);
     }
@@ -1611,14 +1611,14 @@ num_put<_CharT, _OutputIterator>::do_put(iter_type __s, ios_base& __iob,
                                    (int)__iob.precision(), __v);
     else
         __nc = __libcpp_snprintf_l(__nb, __nbuf, _LIBCPP_GET_C_LOCALE, __fmt, __v);
-    unique_ptr<char, void(*)(void*)> __nbh(0, free);
+    unique_ptr<char, void(*)(void*)> __nbh(nullptr, free);
     if (__nc > static_cast<int>(__nbuf-1))
     {
         if (__specify_precision)
             __nc = __libcpp_asprintf_l(&__nb, _LIBCPP_GET_C_LOCALE, __fmt, (int)__iob.precision(), __v);
         else
             __nc = __libcpp_asprintf_l(&__nb, _LIBCPP_GET_C_LOCALE, __fmt, __v);
-        if (__nb == 0)
+        if (__nb == nullptr)
             __throw_bad_alloc();
         __nbh.reset(__nb);
     }
@@ -3104,11 +3104,11 @@ money_get<_CharT, _InputIterator>::do_get(iter_type __b, iter_type __e,
         __ct.widen(__src, __src + (sizeof(__src)-1), __atoms);
         char __nbuf[__bz];
         char* __nc = __nbuf;
-        unique_ptr<char, void(*)(void*)> __h(0, free);
+        unique_ptr<char, void(*)(void*)> __h(nullptr, free);
         if (__wn - __wb.get() > __bz-2)
         {
             __h.reset((char*)malloc(static_cast<size_t>(__wn - __wb.get() + 2)));
-            if (__h.get() == 0)
+            if (__h.get() == nullptr)
                 __throw_bad_alloc();
             __nc = __h.get();
         }
@@ -3393,13 +3393,13 @@ money_put<_CharT, _OutputIterator>::do_put(iter_type __s, bool __intl,
     char_type __digits[__bs];
     char_type* __db = __digits;
     size_t __n = static_cast<size_t>(snprintf(__bb, __bs, "%.0Lf", __units));
-    unique_ptr<char, void(*)(void*)> __hn(0, free);
+    unique_ptr<char, void(*)(void*)> __hn(nullptr, free);
     unique_ptr<char_type, void(*)(void*)> __hd(0, free);
     // secure memory for digit storage
     if (__n > __bs-1)
     {
         __n = static_cast<size_t>(__libcpp_asprintf_l(&__bb, _LIBCPP_GET_C_LOCALE, "%.0Lf", __units));
-        if (__bb == 0)
+        if (__bb == nullptr)
             __throw_bad_alloc();
         __hn.reset(__bb);
         __hd.reset((char_type*)malloc(__n * sizeof(char_type)));
@@ -3919,7 +3919,7 @@ private:
     wbuffer_convert(const wbuffer_convert&);
     wbuffer_convert& operator=(const wbuffer_convert&);
 public:
-    _LIBCPP_EXPLICIT_AFTER_CXX11 wbuffer_convert(streambuf* __bytebuf = 0,
+    _LIBCPP_EXPLICIT_AFTER_CXX11 wbuffer_convert(streambuf* __bytebuf = nullptr,
             _Codecvt* __pcvt = new _Codecvt, state_type __state = state_type());
     ~wbuffer_convert();
 
@@ -3957,9 +3957,9 @@ private:
 template <class _Codecvt, class _Elem, class _Tr>
 wbuffer_convert<_Codecvt, _Elem, _Tr>::
     wbuffer_convert(streambuf* __bytebuf, _Codecvt* __pcvt, state_type __state)
-    : __extbuf_(0),
-      __extbufnext_(0),
-      __extbufend_(0),
+    : __extbuf_(nullptr),
+      __extbufnext_(nullptr),
+      __extbufend_(nullptr),
       __ebs_(0),
       __intbuf_(0),
       __ibs_(0),
@@ -4332,12 +4332,12 @@ template <class _Codecvt, class _Elem, class _Tr>
 wbuffer_convert<_Codecvt, _Elem, _Tr>*
 wbuffer_convert<_Codecvt, _Elem, _Tr>::__close()
 {
-    wbuffer_convert* __rt = 0;
-    if (__cv_ != 0 && __bufptr_ != 0)
+    wbuffer_convert* __rt = nullptr;
+    if (__cv_ != nullptr && __bufptr_ != nullptr)
     {
         __rt = this;
         if ((__cm_ & ios_base::out) && sync())
-            __rt = 0;
+            __rt = nullptr;
     }
     return __rt;
 }
diff --git a/libcxx/include/memory b/libcxx/include/memory
index 52636e9d6835b3..f42f03f53f8032 100644
--- a/libcxx/include/memory
+++ b/libcxx/include/memory
@@ -1912,7 +1912,7 @@ public:
     _LIBCPP_INLINE_VISIBILITY _Tp* release() _NOEXCEPT
     {
         _Tp* __t = __ptr_;
-        __ptr_ = 0;
+        __ptr_ = nullptr;
         return __t;
     }
     _LIBCPP_INLINE_VISIBILITY void reset(_Tp* __p = 0) _NOEXCEPT
@@ -2853,7 +2853,7 @@ public:
         : __size_(__s) {}
 
     template <class _Tp>
-    _LIBCPP_INLINE_VISIBILITY void __incr(_Tp*) _NOEXCEPT
+    _LIBCPP_INLINE_VISIBILITY void __incr() _NOEXCEPT
         {__incr(integral_constant<bool, is_trivially_destructible<_Tp>::value>());}
 
     template <class _Tp>
@@ -3545,7 +3545,7 @@ public:
     _LIBCPP_INLINE_VISIBILITY
     bool unique() const _NOEXCEPT {return use_count() == 1;}
     _LIBCPP_INLINE_VISIBILITY
-    _LIBCPP_EXPLICIT operator bool() const _NOEXCEPT {return get() != 0;}
+    _LIBCPP_EXPLICIT operator bool() const _NOEXCEPT {return get() != nullptr;}
     template <class _Up>
         _LIBCPP_INLINE_VISIBILITY
         bool owner_before(shared_ptr<_Up> const& __p) const _NOEXCEPT
@@ -3649,8 +3649,8 @@ template<class _Tp>
 inline
 _LIBCPP_CONSTEXPR
 shared_ptr<_Tp>::shared_ptr() _NOEXCEPT
-    : __ptr_(0),
-      __cntrl_(0)
+    : __ptr_(nullptr),
+      __cntrl_(nullptr)
 {
 }
 
@@ -3658,8 +3658,8 @@ template<class _Tp>
 inline
 _LIBCPP_CONSTEXPR
 shared_ptr<_Tp>::shared_ptr(nullptr_t) _NOEXCEPT
-    : __ptr_(0),
-      __cntrl_(0)
+    : __ptr_(nullptr),
+      __cntrl_(nullptr)
 {
 }
 
@@ -3704,7 +3704,7 @@ shared_ptr<_Tp>::shared_ptr(_Yp* __p, _Dp __d,
 template<class _Tp>
 template<class _Dp>
 shared_ptr<_Tp>::shared_ptr(nullptr_t __p, _Dp __d)
-    : __ptr_(0)
+    : __ptr_(nullptr)
 {
 #ifndef _LIBCPP_NO_EXCEPTIONS
     try
@@ -3755,7 +3755,7 @@ shared_ptr<_Tp>::shared_ptr(_Yp* __p, _Dp __d, _Alloc __a,
 template<class _Tp>
 template<class _Dp, class _Alloc>
 shared_ptr<_Tp>::shared_ptr(nullptr_t __p, _Dp __d, _Alloc __a)
-    : __ptr_(0)
+    : __ptr_(nullptr)
 {
 #ifndef _LIBCPP_NO_EXCEPTIONS
     try
@@ -3819,8 +3819,8 @@ shared_ptr<_Tp>::shared_ptr(shared_ptr&& __r) _NOEXCEPT
     : __ptr_(__r.__ptr_),
       __cntrl_(__r.__cntrl_)
 {
-    __r.__ptr_ = 0;
-    __r.__cntrl_ = 0;
+    __r.__ptr_ = nullptr;
+    __r.__cntrl_ = nullptr;
 }
 
 template<class _Tp>
@@ -3832,8 +3832,8 @@ shared_ptr<_Tp>::shared_ptr(shared_ptr<_Yp>&& __r,
     : __ptr_(__r.__ptr_),
       __cntrl_(__r.__cntrl_)
 {
-    __r.__ptr_ = 0;
-    __r.__cntrl_ = 0;
+    __r.__ptr_ = nullptr;
+    __r.__cntrl_ = nullptr;
 }
 
 #if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)
@@ -4368,7 +4368,7 @@ public:
         {return __cntrl_ ? __cntrl_->use_count() : 0;}
     _LIBCPP_INLINE_VISIBILITY
     bool expired() const _NOEXCEPT
-        {return __cntrl_ == 0 || __cntrl_->use_count() == 0;}
+        {return __cntrl_ == nullptr || __cntrl_->use_count() == 0;}
     shared_ptr<_Tp> lock() const _NOEXCEPT;
     template<class _Up>
         _LIBCPP_INLINE_VISIBILITY
@@ -4392,8 +4392,8 @@ template<class _Tp>
 inline
 _LIBCPP_CONSTEXPR
 weak_ptr<_Tp>::weak_ptr() _NOEXCEPT
-    : __ptr_(0),
-      __cntrl_(0)
+    : __ptr_(nullptr),
+      __cntrl_(nullptr)
 {
 }
 
@@ -4439,8 +4439,8 @@ weak_ptr<_Tp>::weak_ptr(weak_ptr&& __r) _NOEXCEPT
     : __ptr_(__r.__ptr_),
       __cntrl_(__r.__cntrl_)
 {
-    __r.__ptr_ = 0;
-    __r.__cntrl_ = 0;
+    __r.__ptr_ = nullptr;
+    __r.__cntrl_ = nullptr;
 }
 
 template<class _Tp>
@@ -4452,8 +4452,8 @@ weak_ptr<_Tp>::weak_ptr(weak_ptr<_Yp>&& __r,
     : __ptr_(__r.__ptr_),
       __cntrl_(__r.__cntrl_)
 {
-    __r.__ptr_ = 0;
-    __r.__cntrl_ = 0;
+    __r.__ptr_ = nullptr;
+    __r.__cntrl_ = nullptr;
 }
 
 template<class _Tp>
@@ -4555,7 +4555,7 @@ shared_ptr<_Tp>::shared_ptr(const weak_ptr<_Yp>& __r,
     : __ptr_(__r.__ptr_),
       __cntrl_(__r.__cntrl_ ? __r.__cntrl_->lock() : __r.__cntrl_)
 {
-    if (__cntrl_ == 0)
+    if (__cntrl_ == nullptr)
         __throw_bad_weak_ptr();
 }
 
diff --git a/libcxx/include/regex b/libcxx/include/regex
index e4868af92f5fe8..028831d72e0b7a 100644
--- a/libcxx/include/regex
+++ b/libcxx/include/regex
@@ -2574,12 +2574,12 @@ public:
     _LIBCPP_INLINE_VISIBILITY
     basic_regex()
         : __flags_(regex_constants::ECMAScript), __marked_count_(0), __loop_count_(0), __open_count_(0),
-          __end_(0)
+          __end_(nullptr)
         {}
     _LIBCPP_INLINE_VISIBILITY
     explicit basic_regex(const value_type* __p, flag_type __f = regex_constants::ECMAScript)
         : __flags_(__f), __marked_count_(0), __loop_count_(0), __open_count_(0),
-          __end_(0)
+          __end_(nullptr)
         {
         __init(__p, __p + __traits_.length(__p));
         }
@@ -2587,7 +2587,7 @@ public:
     _LIBCPP_INLINE_VISIBILITY
     basic_regex(const value_type* __p, size_t __len, flag_type __f = regex_constants::ECMAScript)
         : __flags_(__f), __marked_count_(0), __loop_count_(0), __open_count_(0),
-          __end_(0)
+          __end_(nullptr)
         {
         __init(__p, __p + __len);
         }
@@ -2599,7 +2599,7 @@ public:
         explicit basic_regex(const basic_string<value_type, _ST, _SA>& __p,
                              flag_type __f = regex_constants::ECMAScript)
         : __flags_(__f), __marked_count_(0), __loop_count_(0), __open_count_(0),
-          __end_(0)
+          __end_(nullptr)
         {
         __init(__p.begin(), __p.end());
         }
@@ -2609,7 +2609,7 @@ public:
         basic_regex(_ForwardIterator __first, _ForwardIterator __last,
                     flag_type __f = regex_constants::ECMAScript)
         : __flags_(__f), __marked_count_(0), __loop_count_(0), __open_count_(0),
-          __end_(0)
+          __end_(nullptr)
         {
         __init(__first, __last);
         }
@@ -2618,7 +2618,7 @@ public:
     basic_regex(initializer_list<value_type> __il,
                 flag_type __f = regex_constants::ECMAScript)
         : __flags_(__f), __marked_count_(0), __loop_count_(0), __open_count_(0),
-          __end_(0)
+          __end_(nullptr)
         {
         __init(__il.begin(), __il.end());
         }
diff --git a/libcxx/include/sstream b/libcxx/include/sstream
index 1439d9c4ab9c9e..22cc0c3503844b 100644
--- a/libcxx/include/sstream
+++ b/libcxx/include/sstream
@@ -210,13 +210,13 @@ public:
     // 27.8.1.1 Constructors:
     _LIBCPP_INLINE_VISIBILITY
     explicit basic_stringbuf(ios_base::openmode __wch = ios_base::in | ios_base::out)
-        : __hm_(0), __mode_(__wch)
+        : __hm_(nullptr), __mode_(__wch)
     { }
 
     _LIBCPP_INLINE_VISIBILITY
     explicit basic_stringbuf(const string_type& __s,
                              ios_base::openmode __wch = ios_base::in | ios_base::out)
-        : __str_(__s.get_allocator()), __hm_(0), __mode_(__wch)
+        : __str_(__s.get_allocator()), __hm_(nullptr), __mode_(__wch)
     {
         str(__s);
     }
@@ -440,7 +440,7 @@ void
 basic_stringbuf<_CharT, _Traits, _Allocator>::str(const string_type& __s)
 {
     __str_ = __s;
-    __hm_ = 0;
+    __hm_ = nullptr;
     if (__mode_ & ios_base::in)
     {
         __hm_ = const_cast<char_type*>(__str_.data()) + __str_.size();
@@ -587,9 +587,9 @@ basic_stringbuf<_CharT, _Traits, _Allocator>::seekoff(off_type __off,
         return pos_type(-1);
     if (__noff != 0)
     {
-        if ((__wch & ios_base::in) && this->gptr() == 0)
+        if ((__wch & ios_base::in) && this->gptr() == nullptr)
             return pos_type(-1);
-        if ((__wch & ios_base::out) && this->pptr() == 0)
+        if ((__wch & ios_base::out) && this->pptr() == nullptr)
             return pos_type(-1);
     }
     if (__wch & ios_base::in)
diff --git a/libcxx/include/streambuf b/libcxx/include/streambuf
index 193b7e5ae8a612..0dfa31449b9089 100644
--- a/libcxx/include/streambuf
+++ b/libcxx/include/streambuf
@@ -308,12 +308,12 @@ basic_streambuf<_CharT, _Traits>::~basic_streambuf()
 
 template <class _CharT, class _Traits>
 basic_streambuf<_CharT, _Traits>::basic_streambuf()
-    : __binp_(0),
-      __ninp_(0),
-      __einp_(0),
-      __bout_(0),
-      __nout_(0),
-      __eout_(0)
+    : __binp_(nullptr),
+      __ninp_(nullptr),
+      __einp_(nullptr),
+      __bout_(nullptr),
+      __nout_(nullptr),
+      __eout_(nullptr)
 {
 }
 
diff --git a/libcxx/include/string b/libcxx/include/string
index d3e53592f5f106..1f3f444727fd77 100644
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -449,15 +449,15 @@ typedef basic_string<wchar_t> wstring;
 typedef basic_string<char16_t> u16string;
 typedef basic_string<char32_t> u32string;
 
-int                stoi  (const string& str, size_t* idx = 0, int base = 10);
-long               stol  (const string& str, size_t* idx = 0, int base = 10);
-unsigned long      stoul (const string& str, size_t* idx = 0, int base = 10);
-long long          stoll (const string& str, size_t* idx = 0, int base = 10);
-unsigned long long stoull(const string& str, size_t* idx = 0, int base = 10);
+int                stoi  (const string& str, size_t* idx = nullptr, int base = 10);
+long               stol  (const string& str, size_t* idx = nullptr, int base = 10);
+unsigned long      stoul (const string& str, size_t* idx = nullptr, int base = 10);
+long long          stoll (const string& str, size_t* idx = nullptr, int base = 10);
+unsigned long long stoull(const string& str, size_t* idx = nullptr, int base = 10);
 
-float       stof (const string& str, size_t* idx = 0);
-double      stod (const string& str, size_t* idx = 0);
-long double stold(const string& str, size_t* idx = 0);
+float       stof (const string& str, size_t* idx = nullptr);
+double      stod (const string& str, size_t* idx = nullptr);
+long double stold(const string& str, size_t* idx = nullptr);
 
 string to_string(int val);
 string to_string(unsigned val);
@@ -469,15 +469,15 @@ string to_string(float val);
 string to_string(double val);
 string to_string(long double val);
 
-int                stoi  (const wstring& str, size_t* idx = 0, int base = 10);
-long               stol  (const wstring& str, size_t* idx = 0, int base = 10);
-unsigned long      stoul (const wstring& str, size_t* idx = 0, int base = 10);
-long long          stoll (const wstring& str, size_t* idx = 0, int base = 10);
-unsigned long long stoull(const wstring& str, size_t* idx = 0, int base = 10);
+int                stoi  (const wstring& str, size_t* idx = nullptr, int base = 10);
+long               stol  (const wstring& str, size_t* idx = nullptr, int base = 10);
+unsigned long      stoul (const wstring& str, size_t* idx = nullptr, int base = 10);
+long long          stoll (const wstring& str, size_t* idx = nullptr, int base = 10);
+unsigned long long stoull(const wstring& str, size_t* idx = nullptr, int base = 10);
 
-float       stof (const wstring& str, size_t* idx = 0);
-double      stod (const wstring& str, size_t* idx = 0);
-long double stold(const wstring& str, size_t* idx = 0);
+float       stof (const wstring& str, size_t* idx = nullptr);
+double      stod (const wstring& str, size_t* idx = nullptr);
+long double stold(const wstring& str, size_t* idx = nullptr);
 
 wstring to_wstring(int val);
 wstring to_wstring(unsigned val);
@@ -3965,7 +3965,7 @@ basic_string<_CharT, _Traits, _Allocator>::__invariants() const
         return false;
     if (capacity() < __min_cap - 1)
         return false;
-    if (data() == 0)
+    if (data() == nullptr)
         return false;
     if (data()[size()] != value_type())
         return false;
@@ -4336,15 +4336,15 @@ typedef basic_string<char16_t> u16string;
 typedef basic_string<char32_t> u32string;
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
 
-_LIBCPP_FUNC_VIS int                stoi  (const string& __str, size_t* __idx = 0, int __base = 10);
-_LIBCPP_FUNC_VIS long               stol  (const string& __str, size_t* __idx = 0, int __base = 10);
-_LIBCPP_FUNC_VIS unsigned long      stoul (const string& __str, size_t* __idx = 0, int __base = 10);
-_LIBCPP_FUNC_VIS long long          stoll (const string& __str, size_t* __idx = 0, int __base = 10);
-_LIBCPP_FUNC_VIS unsigned long long stoull(const string& __str, size_t* __idx = 0, int __base = 10);
+_LIBCPP_FUNC_VIS int                stoi  (const string& __str, size_t* __idx = nullptr, int __base = 10);
+_LIBCPP_FUNC_VIS long               stol  (const string& __str, size_t* __idx = nullptr, int __base = 10);
+_LIBCPP_FUNC_VIS unsigned long      stoul (const string& __str, size_t* __idx = nullptr, int __base = 10);
+_LIBCPP_FUNC_VIS long long          stoll (const string& __str, size_t* __idx = nullptr, int __base = 10);
+_LIBCPP_FUNC_VIS unsigned long long stoull(const string& __str, size_t* __idx = nullptr, int __base = 10);
 
-_LIBCPP_FUNC_VIS float       stof (const string& __str, size_t* __idx = 0);
-_LIBCPP_FUNC_VIS double      stod (const string& __str, size_t* __idx = 0);
-_LIBCPP_FUNC_VIS long double stold(const string& __str, size_t* __idx = 0);
+_LIBCPP_FUNC_VIS float       stof (const string& __str, size_t* __idx = nullptr);
+_LIBCPP_FUNC_VIS double      stod (const string& __str, size_t* __idx = nullptr);
+_LIBCPP_FUNC_VIS long double stold(const string& __str, size_t* __idx = nullptr);
 
 _LIBCPP_FUNC_VIS string to_string(int __val);
 _LIBCPP_FUNC_VIS string to_string(unsigned __val);
@@ -4356,15 +4356,15 @@ _LIBCPP_FUNC_VIS string to_string(float __val);
 _LIBCPP_FUNC_VIS string to_string(double __val);
 _LIBCPP_FUNC_VIS string to_string(long double __val);
 
-_LIBCPP_FUNC_VIS int                stoi  (const wstring& __str, size_t* __idx = 0, int __base = 10);
-_LIBCPP_FUNC_VIS long               stol  (const wstring& __str, size_t* __idx = 0, int __base = 10);
-_LIBCPP_FUNC_VIS unsigned long      stoul (const wstring& __str, size_t* __idx = 0, int __base = 10);
-_LIBCPP_FUNC_VIS long long          stoll (const wstring& __str, size_t* __idx = 0, int __base = 10);
-_LIBCPP_FUNC_VIS unsigned long long stoull(const wstring& __str, size_t* __idx = 0, int __base = 10);
+_LIBCPP_FUNC_VIS int                stoi  (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
+_LIBCPP_FUNC_VIS long               stol  (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
+_LIBCPP_FUNC_VIS unsigned long      stoul (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
+_LIBCPP_FUNC_VIS long long          stoll (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
+_LIBCPP_FUNC_VIS unsigned long long stoull(const wstring& __str, size_t* __idx = nullptr, int __base = 10);
 
-_LIBCPP_FUNC_VIS float       stof (const wstring& __str, size_t* __idx = 0);
-_LIBCPP_FUNC_VIS double      stod (const wstring& __str, size_t* __idx = 0);
-_LIBCPP_FUNC_VIS long double stold(const wstring& __str, size_t* __idx = 0);
+_LIBCPP_FUNC_VIS float       stof (const wstring& __str, size_t* __idx = nullptr);
+_LIBCPP_FUNC_VIS double      stod (const wstring& __str, size_t* __idx = nullptr);
+_LIBCPP_FUNC_VIS long double stold(const wstring& __str, size_t* __idx = nullptr);
 
 _LIBCPP_FUNC_VIS wstring to_wstring(int __val);
 _LIBCPP_FUNC_VIS wstring to_wstring(unsigned __val);
diff --git a/libcxx/include/strstream b/libcxx/include/strstream
index 31999bbae14b21..6b893eebd00bce 100644
--- a/libcxx/include/strstream
+++ b/libcxx/include/strstream
@@ -19,12 +19,12 @@ class strstreambuf
 public:
     explicit strstreambuf(streamsize alsize_arg = 0);
     strstreambuf(void* (*palloc_arg)(size_t), void (*pfree_arg)(void*));
-    strstreambuf(char* gnext_arg, streamsize n, char* pbeg_arg = 0);
+    strstreambuf(char* gnext_arg, streamsize n, char* pbeg_arg = nullptr);
     strstreambuf(const char* gnext_arg, streamsize n);
 
-    strstreambuf(signed char* gnext_arg, streamsize n, signed char* pbeg_arg = 0);
+    strstreambuf(signed char* gnext_arg, streamsize n, signed char* pbeg_arg = nullptr);
     strstreambuf(const signed char* gnext_arg, streamsize n);
-    strstreambuf(unsigned char* gnext_arg, streamsize n, unsigned char* pbeg_arg = 0);
+    strstreambuf(unsigned char* gnext_arg, streamsize n, unsigned char* pbeg_arg = nullptr);
     strstreambuf(const unsigned char* gnext_arg, streamsize n);
 
     strstreambuf(strstreambuf&& rhs);
@@ -142,12 +142,12 @@ class _LIBCPP_TYPE_VIS strstreambuf
 public:
     explicit strstreambuf(streamsize __alsize = 0);
     strstreambuf(void* (*__palloc)(size_t), void (*__pfree)(void*));
-    strstreambuf(char* __gnext, streamsize __n, char* __pbeg = 0);
+    strstreambuf(char* __gnext, streamsize __n, char* __pbeg = nullptr);
     strstreambuf(const char* __gnext, streamsize __n);
 
-    strstreambuf(signed char* __gnext, streamsize __n, signed char* __pbeg = 0);
+    strstreambuf(signed char* __gnext, streamsize __n, signed char* __pbeg = nullptr);
     strstreambuf(const signed char* __gnext, streamsize __n);
-    strstreambuf(unsigned char* __gnext, streamsize __n, unsigned char* __pbeg = 0);
+    strstreambuf(unsigned char* __gnext, streamsize __n, unsigned char* __pbeg = nullptr);
     strstreambuf(const unsigned char* __gnext, streamsize __n);
 
 #ifndef _LIBCPP_CXX03_LANG
diff --git a/libcxx/include/system_error b/libcxx/include/system_error
index 74e889aa9ac74e..b714e1d4263d1d 100644
--- a/libcxx/include/system_error
+++ b/libcxx/include/system_error
@@ -253,7 +253,7 @@ public:
     template <class _Ep>
         _LIBCPP_INLINE_VISIBILITY
         error_condition(_Ep __e,
-              typename enable_if<is_error_condition_enum<_Ep>::value>::type* = 0
+              typename enable_if<is_error_condition_enum<_Ep>::value>::type* = nullptr
                                                                      ) _NOEXCEPT
             {*this = make_error_condition(__e);}
 
@@ -325,7 +325,7 @@ public:
     template <class _Ep>
         _LIBCPP_INLINE_VISIBILITY
         error_code(_Ep __e,
-                   typename enable_if<is_error_code_enum<_Ep>::value>::type* = 0
+                   typename enable_if<is_error_code_enum<_Ep>::value>::type* = nullptr
                                                                      ) _NOEXCEPT
             {*this = make_error_code(__e);}
 
diff --git a/libcxx/include/valarray b/libcxx/include/valarray
index 4bbd5ed323af9b..aaae6fbd5b3fb8 100644
--- a/libcxx/include/valarray
+++ b/libcxx/include/valarray
@@ -802,7 +802,7 @@ private:
 public:
     // construct/destroy:
     _LIBCPP_INLINE_VISIBILITY
-    valarray() : __begin_(0), __end_(0) {}
+    valarray() : __begin_(nullptr), __end_(nullptr) {}
     inline _LIBCPP_HIDE_FROM_ABI_AFTER_V1
     explicit valarray(size_t __n);
     _LIBCPP_INLINE_VISIBILITY
@@ -2750,8 +2750,8 @@ __val_expr<_ValExpr>::operator valarray<__val_expr::result_type>() const
 template <class _Tp>
 inline
 valarray<_Tp>::valarray(size_t __n)
-    : __begin_(0),
-      __end_(0)
+    : __begin_(nullptr),
+      __end_(nullptr)
 {
     if (__n)
     {
@@ -2776,16 +2776,16 @@ valarray<_Tp>::valarray(size_t __n)
 template <class _Tp>
 inline
 valarray<_Tp>::valarray(const value_type& __x, size_t __n)
-    : __begin_(0),
-      __end_(0)
+    : __begin_(nullptr),
+      __end_(nullptr)
 {
     resize(__n, __x);
 }
 
 template <class _Tp>
 valarray<_Tp>::valarray(const value_type* __p, size_t __n)
-    : __begin_(0),
-      __end_(0)
+    : __begin_(nullptr),
+      __end_(nullptr)
 {
     if (__n)
     {
@@ -2809,8 +2809,8 @@ valarray<_Tp>::valarray(const value_type* __p, size_t __n)
 
 template <class _Tp>
 valarray<_Tp>::valarray(const valarray& __v)
-    : __begin_(0),
-      __end_(0)
+    : __begin_(nullptr),
+      __end_(nullptr)
 {
     if (__v.size())
     {
@@ -2845,8 +2845,8 @@ valarray<_Tp>::valarray(valarray&& __v) _NOEXCEPT
 
 template <class _Tp>
 valarray<_Tp>::valarray(initializer_list<value_type> __il)
-    : __begin_(0),
-      __end_(0)
+    : __begin_(nullptr),
+      __end_(nullptr)
 {
     const size_t __n = __il.size();
     if (__n)
@@ -2874,8 +2874,8 @@ valarray<_Tp>::valarray(initializer_list<value_type> __il)
 
 template <class _Tp>
 valarray<_Tp>::valarray(const slice_array<value_type>& __sa)
-    : __begin_(0),
-      __end_(0)
+    : __begin_(nullptr),
+      __end_(nullptr)
 {
     const size_t __n = __sa.__size_;
     if (__n)
@@ -2901,8 +2901,8 @@ valarray<_Tp>::valarray(const slice_array<value_type>& __sa)
 
 template <class _Tp>
 valarray<_Tp>::valarray(const gslice_array<value_type>& __ga)
-    : __begin_(0),
-      __end_(0)
+    : __begin_(nullptr),
+      __end_(nullptr)
 {
     const size_t __n = __ga.__1d_.size();
     if (__n)
@@ -2930,8 +2930,8 @@ valarray<_Tp>::valarray(const gslice_array<value_type>& __ga)
 
 template <class _Tp>
 valarray<_Tp>::valarray(const mask_array<value_type>& __ma)
-    : __begin_(0),
-      __end_(0)
+    : __begin_(nullptr),
+      __end_(nullptr)
 {
     const size_t __n = __ma.__1d_.size();
     if (__n)
@@ -2959,8 +2959,8 @@ valarray<_Tp>::valarray(const mask_array<value_type>& __ma)
 
 template <class _Tp>
 valarray<_Tp>::valarray(const indirect_array<value_type>& __ia)
-    : __begin_(0),
-      __end_(0)
+    : __begin_(nullptr),
+      __end_(nullptr)
 {
     const size_t __n = __ia.__1d_.size();
     if (__n)
diff --git a/libcxx/src/new.cpp b/libcxx/src/new.cpp
index 57f948fbb052b5..8bdaf13cf95328 100644
--- a/libcxx/src/new.cpp
+++ b/libcxx/src/new.cpp
@@ -64,7 +64,7 @@ operator new(std::size_t size) _THROW_BAD_ALLOC
     if (size == 0)
         size = 1;
     void* p;
-    while ((p = ::malloc(size)) == 0)
+    while ((p = ::malloc(size)) == nullptr)
     {
         // If malloc fails and there is a new_handler,
         // call it to try free up memory.
@@ -85,7 +85,7 @@ _LIBCPP_WEAK
 void*
 operator new(size_t size, const std::nothrow_t&) _NOEXCEPT
 {
-    void* p = 0;
+    void* p = nullptr;
 #ifndef _LIBCPP_NO_EXCEPTIONS
     try
     {
@@ -111,7 +111,7 @@ _LIBCPP_WEAK
 void*
 operator new[](size_t size, const std::nothrow_t&) _NOEXCEPT
 {
-    void* p = 0;
+    void* p = nullptr;
 #ifndef _LIBCPP_NO_EXCEPTIONS
     try
     {
@@ -207,7 +207,7 @@ _LIBCPP_WEAK
 void*
 operator new(size_t size, std::align_val_t alignment, const std::nothrow_t&) _NOEXCEPT
 {
-    void* p = 0;
+    void* p = nullptr;
 #ifndef _LIBCPP_NO_EXCEPTIONS
     try
     {
@@ -233,7 +233,7 @@ _LIBCPP_WEAK
 void*
 operator new[](size_t size, std::align_val_t alignment, const std::nothrow_t&) _NOEXCEPT
 {
-    void* p = 0;
+    void* p = nullptr;
 #ifndef _LIBCPP_NO_EXCEPTIONS
     try
     {
diff --git a/libcxxabi/src/stdlib_new_delete.cpp b/libcxxabi/src/stdlib_new_delete.cpp
index 643108f2969164..9df84548ea3ecb 100644
--- a/libcxxabi/src/stdlib_new_delete.cpp
+++ b/libcxxabi/src/stdlib_new_delete.cpp
@@ -27,7 +27,7 @@ operator new(std::size_t size) _THROW_BAD_ALLOC
     if (size == 0)
         size = 1;
     void* p;
-    while ((p = ::malloc(size)) == 0)
+    while ((p = ::malloc(size)) == nullptr)
     {
         // If malloc fails and there is a new_handler,
         // call it to try free up memory.
@@ -48,7 +48,7 @@ _LIBCXXABI_WEAK
 void*
 operator new(size_t size, const std::nothrow_t&) _NOEXCEPT
 {
-    void* p = 0;
+    void* p = nullptr;
 #ifndef _LIBCXXABI_NO_EXCEPTIONS
     try
     {
@@ -74,7 +74,7 @@ _LIBCXXABI_WEAK
 void*
 operator new[](size_t size, const std::nothrow_t&) _NOEXCEPT
 {
-    void* p = 0;
+    void* p = nullptr;
 #ifndef _LIBCXXABI_NO_EXCEPTIONS
     try
     {
@@ -170,7 +170,7 @@ _LIBCXXABI_WEAK
 void*
 operator new(size_t size, std::align_val_t alignment, const std::nothrow_t&) _NOEXCEPT
 {
-    void* p = 0;
+    void* p = nullptr;
 #ifndef _LIBCXXABI_NO_EXCEPTIONS
     try
     {
@@ -196,7 +196,7 @@ _LIBCXXABI_WEAK
 void*
 operator new[](size_t size, std::align_val_t alignment, const std::nothrow_t&) _NOEXCEPT
 {
-    void* p = 0;
+    void* p = nullptr;
 #ifndef _LIBCXXABI_NO_EXCEPTIONS
     try
     {