Index: include/variant
===================================================================
--- include/variant
+++ include/variant
@@ -1092,16 +1092,42 @@
 struct __overload;
 
 template <>
-struct __overload<> { void operator()() const; };
+struct __overload<>
+{
+    static void test();
+};
 
 template <class _Tp, class... _Types>
-struct __overload<_Tp, _Types...> : __overload<_Types...> {
-  using __overload<_Types...>::operator();
-  __identity<_Tp> operator()(_Tp) const;
+struct __overload<_Tp, _Types...> : __overload<_Types...>
+{
+    using __overload<_Types...>::test;
+
+    template <class _Up>
+    static auto test(_Tp, _Up&& __t) -> decltype(_Tp{__t}, __identity<_Tp>());
 };
 
+#define _LIBCPP_VARIANT_BOOLEAN_CONVERSION(bool_type)                        \
+    template <class... _Types>                                               \
+    struct __overload<bool_type, _Types...> : __overload<_Types...>          \
+    {                                                                        \
+        using __overload<_Types...>::test;                                   \
+                                                                             \
+        template <class _Up, class _Ap = __uncvref_t<_Up>>                   \
+        static auto test(bool, _Up&&) -> enable_if_t<                        \
+            disjunction_v<is_same<_Ap, bool>, is_class<_Ap>, is_union<_Ap>>, \
+            __identity<bool_type>>;                                          \
+    }
+
+_LIBCPP_VARIANT_BOOLEAN_CONVERSION(bool);
+_LIBCPP_VARIANT_BOOLEAN_CONVERSION(bool const);
+_LIBCPP_VARIANT_BOOLEAN_CONVERSION(bool volatile);
+_LIBCPP_VARIANT_BOOLEAN_CONVERSION(bool const volatile);
+
+#undef _LIBCPP_VARIANT_BOOLEAN_CONVERSION
+
 template <class _Tp, class... _Types>
-using __best_match_t = typename result_of_t<__overload<_Types...>(_Tp&&)>::type;
+using __best_match_t = typename decltype(
+    __overload<_Types...>::test(declval<_Tp>(), declval<_Tp>()))::type;
 
 } // __variant_detail
 
Index: test/std/utilities/variant/variant.variant/variant.assign/T.pass.cpp
===================================================================
--- test/std/utilities/variant/variant.variant/variant.assign/T.pass.cpp
+++ test/std/utilities/variant/variant.variant/variant.assign/T.pass.cpp
@@ -28,6 +28,7 @@
 #include <string>
 #include <type_traits>
 #include <variant>
+#include <memory>
 
 #include "test_macros.h"
 #include "variant_test_helpers.hpp"
@@ -128,7 +129,7 @@
 
 void test_T_assignment_sfinae() {
   {
-    using V = std::variant<long, unsigned>;
+    using V = std::variant<long, long long>;
     static_assert(!std::is_assignable<V, int>::value, "ambiguous");
   }
   {
@@ -139,6 +140,15 @@
     using V = std::variant<std::string, void *>;
     static_assert(!std::is_assignable<V, int>::value, "no matching operator=");
   }
+  {
+    using V = std::variant<std::string, float>;
+    static_assert(!std::is_assignable<V, int>::value, "no matching operator=");
+  }
+  {
+    using V = std::variant<std::unique_ptr<int>, bool>;
+    static_assert(!std::is_assignable<V, std::unique_ptr<char>>::value,
+                  "no explicit bool in operator=");
+  }
 #if !defined(TEST_VARIANT_HAS_NO_REFERENCES)
   {
     using V = std::variant<int, int &&>;
@@ -167,6 +177,33 @@
     assert(v.index() == 1);
     assert(std::get<1>(v) == 43);
   }
+  {
+    std::variant<unsigned, long> v;
+    v = 42;
+    assert(v.index() == 1);
+    assert(std::get<1>(v) == 42);
+    v = 43u;
+    assert(v.index() == 0);
+    assert(std::get<0>(v) == 43);
+  }
+  {
+    std::variant<std::string, bool> v = true;
+    v = std::false_type();
+    assert(v.index() == 1);
+    assert(std::get<1>(v) == false);
+    v = "bar";
+    assert(v.index() == 0);
+    assert(std::get<0>(v) == "bar");
+  }
+  {
+    std::variant<bool, std::unique_ptr<int>> v;
+    v = nullptr;
+    assert(v.index() == 1);
+    assert(std::get<1>(v) == nullptr);
+    v = std::true_type();
+    assert(v.index() == 0);
+    assert(std::get<0>(v));
+  }
 #if !defined(TEST_VARIANT_HAS_NO_REFERENCES)
   {
     using V = std::variant<int &, int &&, long>;
Index: test/std/utilities/variant/variant.variant/variant.ctor/T.pass.cpp
===================================================================
--- test/std/utilities/variant/variant.variant/variant.ctor/T.pass.cpp
+++ test/std/utilities/variant/variant.variant/variant.ctor/T.pass.cpp
@@ -20,6 +20,7 @@
 #include <string>
 #include <type_traits>
 #include <variant>
+#include <memory>
 
 #include "test_convertible.hpp"
 #include "test_macros.h"
@@ -53,7 +54,7 @@
 
 void test_T_ctor_sfinae() {
   {
-    using V = std::variant<long, unsigned>;
+    using V = std::variant<long, long long>;
     static_assert(!std::is_constructible<V, int>::value, "ambiguous");
   }
   {
@@ -66,6 +67,16 @@
                   "no matching constructor");
   }
   {
+    using V = std::variant<std::string, float>;
+    static_assert(!std::is_constructible<V, int>::value,
+                  "no matching constructor");
+  }
+  {
+    using V = std::variant<std::unique_ptr<int>, bool>;
+    static_assert(!std::is_constructible<V, std::unique_ptr<char>>::value,
+                  "no explicit bool in constructor");
+  }
+  {
     using V = std::variant<AnyConstructible, NoConstructible>;
     static_assert(
         !std::is_constructible<V, std::in_place_type_t<NoConstructible>>::value,
@@ -99,6 +110,21 @@
     static_assert(v.index() == 1, "");
     static_assert(std::get<1>(v) == 42, "");
   }
+  {
+    constexpr std::variant<unsigned, long> v(42);
+    static_assert(v.index() == 1, "");
+    static_assert(std::get<1>(v) == 42, "");
+  }
+  {
+    std::variant<std::string, bool const> v = "foo";
+    assert(v.index() == 0);
+    assert(std::get<0>(v) == "foo");
+  }
+  {
+    std::variant<bool volatile, std::unique_ptr<int>> v = nullptr;
+    assert(v.index() == 1);
+    assert(std::get<1>(v) == nullptr);
+  }
 #if !defined(TEST_VARIANT_HAS_NO_REFERENCES)
   {
     using V = std::variant<const int &, int &&, long>;