diff --git a/libcxx/include/__chrono/duration.h b/libcxx/include/__chrono/duration.h
--- a/libcxx/include/__chrono/duration.h
+++ b/libcxx/include/__chrono/duration.h
@@ -212,7 +212,7 @@
         static const intmax_t __d1 = _R1::den / __gcd_d1_d2;
         static const intmax_t __n2 = _R2::num / __gcd_n1_n2;
         static const intmax_t __d2 = _R2::den / __gcd_d1_d2;
-        static const intmax_t max = -((intmax_t(1) << (sizeof(intmax_t) * CHAR_BIT - 1)) + 1);
+        static const intmax_t max = numeric_limits<intmax_t>::max();
 
         template <intmax_t _Xp, intmax_t _Yp, bool __overflow>
         struct __mul    // __overflow == false
diff --git a/libcxx/include/__memory/temporary_buffer.h b/libcxx/include/__memory/temporary_buffer.h
--- a/libcxx/include/__memory/temporary_buffer.h
+++ b/libcxx/include/__memory/temporary_buffer.h
@@ -14,6 +14,7 @@
 #include <__type_traits/alignment_of.h>
 #include <__utility/pair.h>
 #include <cstddef>
+#include <limits>
 #include <new>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -28,9 +29,7 @@
 get_temporary_buffer(ptrdiff_t __n) _NOEXCEPT
 {
     pair<_Tp*, ptrdiff_t> __r(0, 0);
-    const ptrdiff_t __m = (~ptrdiff_t(0) ^
-                           ptrdiff_t(ptrdiff_t(1) << (sizeof(ptrdiff_t) * __CHAR_BIT__ - 1)))
-                           / sizeof(_Tp);
+    const ptrdiff_t __m = (~ptrdiff_t(0) ^ numeric_limits<ptrdiff_t>::min()) / sizeof(_Tp);
     if (__n > __m)
         __n = __m;
     while (__n > 0)
diff --git a/libcxx/include/ratio b/libcxx/include/ratio
--- a/libcxx/include/ratio
+++ b/libcxx/include/ratio
@@ -79,8 +79,8 @@
 
 #include <__assert> // all public C++ headers provide the assertion handler
 #include <__config>
-#include <climits>
 #include <cstdint>
+#include <limits>
 #include <type_traits>
 #include <version>
 
@@ -140,8 +140,8 @@
 template <intmax_t _Xp, intmax_t _Yp>
 class __ll_add<_Xp, _Yp, 1>
 {
-    static const intmax_t min = (1LL << (sizeof(intmax_t) * CHAR_BIT - 1)) + 1;
-    static const intmax_t max = -min;
+    static const intmax_t min = numeric_limits<intmax_t>::min() + 1;
+    static const intmax_t max = numeric_limits<intmax_t>::max();
 
     static_assert(_Xp <= max - _Yp, "overflow in __ll_add");
 public:
@@ -158,8 +158,8 @@
 template <intmax_t _Xp, intmax_t _Yp>
 class __ll_add<_Xp, _Yp, -1>
 {
-    static const intmax_t min = (1LL << (sizeof(intmax_t) * CHAR_BIT - 1)) + 1;
-    static const intmax_t max = -min;
+    static const intmax_t min = numeric_limits<intmax_t>::min() + 1;
+    static const intmax_t max = numeric_limits<intmax_t>::max();
 
     static_assert(min - _Yp <= _Xp, "overflow in __ll_add");
 public:
@@ -172,8 +172,8 @@
 template <intmax_t _Xp, intmax_t _Yp>
 class __ll_sub<_Xp, _Yp, 1>
 {
-    static const intmax_t min = (1LL << (sizeof(intmax_t) * CHAR_BIT - 1)) + 1;
-    static const intmax_t max = -min;
+    static const intmax_t min = numeric_limits<intmax_t>::min() + 1;
+    static const intmax_t max = numeric_limits<intmax_t>::max();
 
     static_assert(min + _Yp <= _Xp, "overflow in __ll_sub");
 public:
@@ -190,8 +190,8 @@
 template <intmax_t _Xp, intmax_t _Yp>
 class __ll_sub<_Xp, _Yp, -1>
 {
-    static const intmax_t min = (1LL << (sizeof(intmax_t) * CHAR_BIT - 1)) + 1;
-    static const intmax_t max = -min;
+    static const intmax_t min = numeric_limits<intmax_t>::min() + 1;
+    static const intmax_t max = numeric_limits<intmax_t>::max();
 
     static_assert(_Xp <= max + _Yp, "overflow in __ll_sub");
 public:
@@ -201,9 +201,9 @@
 template <intmax_t _Xp, intmax_t _Yp>
 class __ll_mul
 {
-    static const intmax_t nan = (1LL << (sizeof(intmax_t) * CHAR_BIT - 1));
-    static const intmax_t min = nan + 1;
-    static const intmax_t max = -min;
+    static const intmax_t nan = numeric_limits<intmax_t>::min();
+    static const intmax_t min = numeric_limits<intmax_t>::min() + 1;
+    static const intmax_t max = numeric_limits<intmax_t>::max();
     static const intmax_t __a_x = __static_abs<_Xp>::value;
     static const intmax_t __a_y = __static_abs<_Yp>::value;
 
@@ -237,9 +237,9 @@
 template <intmax_t _Xp, intmax_t _Yp>
 class __ll_div
 {
-    static const intmax_t nan = (1LL << (sizeof(intmax_t) * CHAR_BIT - 1));
-    static const intmax_t min = nan + 1;
-    static const intmax_t max = -min;
+    static const intmax_t nan = numeric_limits<intmax_t>::min();
+    static const intmax_t min = numeric_limits<intmax_t>::min() + 1;
+    static const intmax_t max = numeric_limits<intmax_t>::max();
 
     static_assert(_Xp != nan && _Yp != nan && _Yp != 0, "overflow in __ll_div");
 public:
diff --git a/libcxx/utils/libcxx/test/params.py b/libcxx/utils/libcxx/test/params.py
--- a/libcxx/utils/libcxx/test/params.py
+++ b/libcxx/utils/libcxx/test/params.py
@@ -15,6 +15,7 @@
   '-Wall',
   '-Wextra',
   '-Wshadow',
+  '-Wshift-sign-overflow',
   '-Wundef',
   '-Wno-unused-command-line-argument',
   '-Wno-attributes',