diff --git a/libcxx/test/std/strings/basic.string/allocator_mismatch.compile.fail.cpp b/libcxx/test/std/strings/basic.string/allocator_mismatch.verify.cpp
rename from libcxx/test/std/strings/basic.string/allocator_mismatch.compile.fail.cpp
rename to libcxx/test/std/strings/basic.string/allocator_mismatch.verify.cpp
--- a/libcxx/test/std/strings/basic.string/allocator_mismatch.compile.fail.cpp
+++ b/libcxx/test/std/strings/basic.string/allocator_mismatch.verify.cpp
@@ -11,9 +11,4 @@
 
 #include <string>
 
-int main(int, char**)
-{
-    std::basic_string<char, std::char_traits<char>, std::allocator<int> > s;
-
-  return 0;
-}
+std::basic_string<char, std::char_traits<char>, std::allocator<int> > s; // expected-error@*:* {{Allocator::value_type must be same type as value_type}}
diff --git a/libcxx/test/std/strings/basic.string/char.bad.fail.cpp b/libcxx/test/std/strings/basic.string/char.bad.fail.cpp
deleted file mode 100644
--- a/libcxx/test/std/strings/basic.string/char.bad.fail.cpp
+++ /dev/null
@@ -1,54 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// 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
-//
-//===----------------------------------------------------------------------===//
-
-// <string>
-//   ... manipulating sequences of any non-array trivial standard-layout types.
-
-#include <string>
-#include "test_traits.h"
-
-struct NotTrivial {
-    NotTrivial() : value(3) {}
-    int value;
-};
-
-struct NotStandardLayout {
-public:
-    NotStandardLayout() : one(1), two(2) {}
-    int sum() const { return one + two; } // silences "unused field 'two' warning"
-    int one;
-private:
-    int two;
-};
-
-int main(int, char**)
-{
-    {
-//  array
-    typedef char C[3];
-    static_assert(std::is_array<C>::value, "");
-    std::basic_string<C, test_traits<C> > s;
-//  expected-error-re@string:* {{static_assert failed{{.*}} "Character type of basic_string must not be an array"}}
-    }
-
-    {
-//  not trivial
-    static_assert(!std::is_trivial<NotTrivial>::value, "");
-    std::basic_string<NotTrivial, test_traits<NotTrivial> > s;
-//  expected-error-re@string:* {{static_assert failed{{.*}} "Character type of basic_string must be trivial"}}
-    }
-
-    {
-//  not standard layout
-    static_assert(!std::is_standard_layout<NotStandardLayout>::value, "");
-    std::basic_string<NotStandardLayout, test_traits<NotStandardLayout> > s;
-//  expected-error-re@string:* {{static_assert failed{{.*}} "Character type of basic_string must be standard-layout"}}
-    }
-
-  return 0;
-}
diff --git a/libcxx/test/std/strings/basic.string/char.bad.verify.cpp b/libcxx/test/std/strings/basic.string/char.bad.verify.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/strings/basic.string/char.bad.verify.cpp
@@ -0,0 +1,51 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+//   ... manipulating sequences of any non-array trivial standard-layout types.
+
+#include <string>
+#include "test_traits.h"
+
+struct NotTrivial {
+    NotTrivial() : value(3) {}
+    int value;
+};
+
+struct NotStandardLayout {
+public:
+    NotStandardLayout() : one(1), two(2) {}
+    int sum() const { return one + two; } // silences "unused field 'two' warning"
+    int one;
+private:
+    int two;
+};
+
+void f() {
+    {
+        // array
+        typedef char C[3];
+        static_assert(std::is_array<C>::value, "");
+        std::basic_string<C, test_traits<C> > s;
+        // expected-error-re@string:* {{static_assert failed{{.*}} "Character type of basic_string must not be an array"}}
+    }
+
+    {
+        // not trivial
+        static_assert(!std::is_trivial<NotTrivial>::value, "");
+        std::basic_string<NotTrivial, test_traits<NotTrivial> > s;
+        // expected-error-re@string:* {{static_assert failed{{.*}} "Character type of basic_string must be trivial"}}
+    }
+
+    {
+        // not standard layout
+        static_assert(!std::is_standard_layout<NotStandardLayout>::value, "");
+        std::basic_string<NotStandardLayout, test_traits<NotStandardLayout> > s;
+        // expected-error-re@string:* {{static_assert failed{{.*}} "Character type of basic_string must be standard-layout"}}
+    }
+}
diff --git a/libcxx/test/std/strings/basic.string/string.cons/iter_alloc_deduction.fail.cpp b/libcxx/test/std/strings/basic.string/string.cons/iter_alloc_deduction.fail.cpp
deleted file mode 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/iter_alloc_deduction.fail.cpp
+++ /dev/null
@@ -1,55 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// 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
-//
-//===----------------------------------------------------------------------===//
-
-// <string>
-// UNSUPPORTED: c++03, c++11, c++14
-
-// template<class InputIterator,
-//      class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
-//  basic_string(InputIterator, InputIterator, Allocator = Allocator())
-//    -> basic_string<typename iterator_traits<InputIterator>::value_type,
-//                 char_traits<typename iterator_traits<InputIterator>::value_type>,
-//                 Allocator>;
-//
-//  The deduction guide shall not participate in overload resolution if InputIterator
-//  is a type that does not qualify as an input iterator, or if Allocator is a type
-//  that does not qualify as an allocator.
-
-
-#include <string>
-#include <iterator>
-#include <cassert>
-#include <cstddef>
-
-#include "test_macros.h"
-
-class NotAnIterator {};
-
-template <typename T>
-struct NotAnAllocator { typedef T value_type; };
-
-int main(int, char**)
-{
-    { // Not an iterator at all
-    std::basic_string s1{NotAnIterator{}, NotAnIterator{}, std::allocator<char>{}}; // expected-error {{no viable constructor or deduction guide for deduction of template arguments of 'basic_string'}}
-    }
-    { // Not an input iterator
-    std::basic_string<char16_t> s0;
-    std::basic_string s1{std::back_insert_iterator(s0), //  expected-error {{no viable constructor or deduction guide for deduction of template arguments of 'basic_string'}}
-                         std::back_insert_iterator(s0),
-                         std::allocator<char16_t>{}};
-    }
-    { // Not an allocator
-    const wchar_t* s = L"12345678901234";
-    (void)s;
-    std::basic_string s1{s, s+10, NotAnAllocator<wchar_t>{}}; // expected-error {{no viable constructor or deduction guide for deduction of template arguments of 'basic_string'}}
-    }
-
-
-  return 0;
-}
diff --git a/libcxx/test/std/strings/basic.string/string.cons/iter_alloc_deduction.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/iter_alloc_deduction.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.cons/iter_alloc_deduction.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/iter_alloc_deduction.pass.cpp
@@ -9,10 +9,6 @@
 // <string>
 // UNSUPPORTED: c++03, c++11, c++14
 
-// template<class InputIterator>
-//   basic_string(InputIterator begin, InputIterator end,
-//   const Allocator& a = Allocator());
-
 // template<class InputIterator,
 //      class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
 //  basic_string(InputIterator, InputIterator, Allocator = Allocator())
@@ -24,15 +20,35 @@
 //  is a type that does not qualify as an input iterator, or if Allocator is a type
 //  that does not qualify as an allocator.
 
-#include <string>
-#include <iterator>
 #include <cassert>
 #include <cstddef>
+#include <iterator>
+#include <string>
+#include <type_traits>
 
 #include "test_macros.h"
 #include "test_allocator.h"
 #include "min_allocator.h"
 
+class NotAnIterator {};
+using NotAnInputIterator = std::back_insert_iterator<std::basic_string<char16_t>>;
+
+template <typename T>
+struct NotAnAllocator { typedef T value_type; };
+
+template <class Iter, class Alloc, class = void>
+struct CanDeduce : std::false_type { };
+
+template <class Iter, class Alloc>
+struct CanDeduce<Iter, Alloc, decltype((void)
+  std::basic_string{std::declval<Iter>(), std::declval<Iter>(), std::declval<Alloc>()}
+)> : std::true_type { };
+
+static_assert( CanDeduce<int*, std::allocator<int>>::value);
+static_assert(!CanDeduce<NotAnIterator, std::allocator<char>>::value);
+static_assert(!CanDeduce<NotAnInputIterator, std::allocator<char16_t>>::value);
+static_assert(!CanDeduce<wchar_t const*, NotAnAllocator<wchar_t>>::value);
+
 bool test() {
   {
     const char* s = "12345678901234";
@@ -90,6 +106,10 @@
 
 int main(int, char**)
 {
+  test();
+#if TEST_STD_VER > 17
+  // static_assert(test());
+#endif
 
   return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/string_view.compile.fail.cpp b/libcxx/test/std/strings/basic.string/string.cons/string_view.compile.fail.cpp
deleted file mode 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/string_view.compile.fail.cpp
+++ /dev/null
@@ -1,24 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// 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
-//
-//===----------------------------------------------------------------------===//
-
-// <string>
-
-// explicit basic_string(basic_string_view<CharT, traits> sv, const Allocator& a = Allocator());
-
-#include <string>
-#include <string_view>
-
-void foo ( const string &s ) {}
-
-int main(int, char**)
-{
-    std::string_view sv = "ABCDE";
-    foo(sv);    // requires implicit conversion from string_view to string
-
-  return 0;
-}
diff --git a/libcxx/test/std/strings/basic.string/string.cons/string_view.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/string_view.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.cons/string_view.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/string_view.pass.cpp
@@ -10,15 +10,19 @@
 
 // explicit basic_string(basic_string_view<CharT, traits> sv, const Allocator& a = Allocator());
 
-#include <string>
-#include <string_view>
-#include <stdexcept>
 #include <algorithm>
 #include <cassert>
+#include <stdexcept>
+#include <string_view>
+#include <string>
+#include <type_traits>
 
-#include "test_macros.h"
-#include "test_allocator.h"
 #include "min_allocator.h"
+#include "test_allocator.h"
+#include "test_macros.h"
+
+static_assert(!std::is_convertible<std::string_view, std::string const&>::value, "");
+static_assert(!std::is_convertible<std::string_view, std::string>::value, "");
 
 template <class charT>
 TEST_CONSTEXPR_CXX20 void
diff --git a/libcxx/test/std/strings/basic.string/string.cons/string_view_deduction.fail.cpp b/libcxx/test/std/strings/basic.string/string.cons/string_view_deduction.fail.cpp
deleted file mode 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/string_view_deduction.fail.cpp
+++ /dev/null
@@ -1,40 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// 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
-//
-//===----------------------------------------------------------------------===//
-
-// <string>
-// UNSUPPORTED: c++03, c++11, c++14
-
-// template<class InputIterator>
-//   basic_string(InputIterator begin, InputIterator end,
-//   const Allocator& a = Allocator());
-
-// template<class charT,
-//          class traits,
-//          class Allocator = allocator<charT>
-//          >
-// basic_string(basic_string_view<charT, traits>, const Allocator& = Allocator())
-//   -> basic_string<charT, traits, Allocator>;
-//
-//  The deduction guide shall not participate in overload resolution if Allocator
-//  is a type that does not qualify as an allocator.
-
-#include <string>
-#include <string_view>
-#include <iterator>
-#include <cassert>
-#include <cstddef>
-
-int main(int, char**)
-{
-    {
-    std::string_view sv = "12345678901234";
-    std::basic_string s1{sv, 23}; // expected-error {{no viable constructor or deduction guide for deduction of template arguments of 'basic_string'}}
-    }
-
-  return 0;
-}
diff --git a/libcxx/test/std/strings/basic.string/string.cons/string_view_deduction.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/string_view_deduction.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.cons/string_view_deduction.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/string_view_deduction.pass.cpp
@@ -9,10 +9,6 @@
 // <string>
 // UNSUPPORTED: c++03, c++11, c++14
 
-// template<class InputIterator>
-//   basic_string(InputIterator begin, InputIterator end,
-//   const Allocator& a = Allocator());
-
 // template<class charT,
 //          class traits,
 //          class Allocator = allocator<charT>
@@ -35,6 +31,18 @@
 #include "test_allocator.h"
 #include "min_allocator.h"
 
+template <class StringView, class Allocator, class = void>
+struct CanDeduce : std::false_type { };
+
+template <class StringView, class Allocator>
+struct CanDeduce<StringView, Allocator, decltype((void)
+  std::basic_string{std::declval<StringView>(), std::declval<Allocator>()}
+)> : std::true_type { };
+
+struct NotAnAllocator { };
+static_assert( CanDeduce<std::string_view, std::allocator<char>>::value);
+static_assert(!CanDeduce<std::string_view, NotAnAllocator>::value);
+
 bool test() {
   {
     std::string_view sv = "12345678901234";
diff --git a/libcxx/test/std/strings/basic.string/string.cons/string_view_size_size_deduction.fail.cpp b/libcxx/test/std/strings/basic.string/string.cons/string_view_size_size_deduction.fail.cpp
deleted file mode 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/string_view_size_size_deduction.fail.cpp
+++ /dev/null
@@ -1,46 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// 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
-//
-//===----------------------------------------------------------------------===//
-
-// <string>
-// UNSUPPORTED: c++03, c++11, c++14
-
-// template<class InputIterator>
-//   basic_string(InputIterator begin, InputIterator end,
-//   const Allocator& a = Allocator());
-
-// template<class charT,
-//          class traits,
-//          class Allocator = allocator<charT>
-//          >
-// basic_string(basic_string_view<charT, traits>,
-//                typename see below::size_type,
-//                typename see below::size_type,
-//                const Allocator& = Allocator())
-//   -> basic_string<charT, traits, Allocator>;
-//
-//  A size_type parameter type in a basic_string deduction guide refers to the size_type
-//  member type of the type deduced by the deduction guide.
-//
-//  The deduction guide shall not participate in overload resolution if Allocator
-//  is a type that does not qualify as an allocator.
-
-#include <string>
-#include <string_view>
-#include <iterator>
-#include <cassert>
-#include <cstddef>
-
-int main(int, char**)
-{
-    {
-    std::string_view sv = "12345678901234";
-    std::basic_string s1{sv, 0, 4, 23}; // expected-error {{no viable constructor or deduction guide for deduction of template arguments of 'basic_string'}}
-    }
-
-  return 0;
-}
diff --git a/libcxx/test/std/strings/basic.string/string.cons/string_view_size_size_deduction.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/string_view_size_size_deduction.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.cons/string_view_size_size_deduction.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/string_view_size_size_deduction.pass.cpp
@@ -9,10 +9,6 @@
 // <string>
 // UNSUPPORTED: c++03, c++11, c++14
 
-// template<class InputIterator>
-//   basic_string(InputIterator begin, InputIterator end,
-//   const Allocator& a = Allocator());
-
 // template<class charT,
 //          class traits,
 //          class Allocator = allocator<charT>
@@ -39,6 +35,18 @@
 #include "test_allocator.h"
 #include "min_allocator.h"
 
+template <class StringView, class Size, class Allocator, class = void>
+struct CanDeduce : std::false_type { };
+
+template <class StringView, class Size, class Allocator>
+struct CanDeduce<StringView, Size, Allocator, decltype((void)
+  std::basic_string{std::declval<StringView>(), std::declval<Size>(), std::declval<Size>(), std::declval<Allocator>()}
+)> : std::true_type { };
+
+struct NotAnAllocator { };
+static_assert( CanDeduce<std::string_view, std::size_t, std::allocator<char>>::value);
+static_assert(!CanDeduce<std::string_view, std::size_t, NotAnAllocator>::value);
+
 bool test() {
   {
     std::string_view sv = "12345678901234";
diff --git a/libcxx/test/std/strings/basic.string/traits_mismatch.compile.fail.cpp b/libcxx/test/std/strings/basic.string/traits_mismatch.verify.cpp
rename from libcxx/test/std/strings/basic.string/traits_mismatch.compile.fail.cpp
rename to libcxx/test/std/strings/basic.string/traits_mismatch.verify.cpp
--- a/libcxx/test/std/strings/basic.string/traits_mismatch.compile.fail.cpp
+++ b/libcxx/test/std/strings/basic.string/traits_mismatch.verify.cpp
@@ -11,9 +11,4 @@
 
 #include <string>
 
-int main(int, char**)
-{
-    std::basic_string<char, std::char_traits<wchar_t>> s;
-
-  return 0;
-}
+std::basic_string<char, std::char_traits<wchar_t> > s; // expected-error@*:* {{traits_type::char_type must be the same type as CharT}}