diff --git a/libcxx/test/std/strings/basic.string/cpp17_input_iterator.h b/libcxx/test/std/strings/basic.string/cpp17_input_iterator.h
deleted file mode 100644
--- a/libcxx/test/std/strings/basic.string/cpp17_input_iterator.h
+++ /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
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef INPUT_ITERATOR_H
-#define INPUT_ITERATOR_H
-
-#include <iterator>
-
-template <class It>
-class cpp17_input_iterator
-{
-    It it_;
-public:
-    typedef typename std::input_iterator_tag                   iterator_category;
-    typedef typename std::iterator_traits<It>::value_type      value_type;
-    typedef typename std::iterator_traits<It>::difference_type difference_type;
-    typedef It                                                 pointer;
-    typedef typename std::iterator_traits<It>::reference       reference;
-
-    cpp17_input_iterator() : it_() {}
-    explicit cpp17_input_iterator(It it) : it_(it) {}
-
-    reference operator*() const {return *it_;}
-    pointer operator->() const {return it_;}
-
-    cpp17_input_iterator& operator++() {++it_; return *this;}
-    cpp17_input_iterator operator++(int) {cpp17_input_iterator tmp(*this); ++(*this); return tmp;}
-
-    friend bool operator==(const cpp17_input_iterator& x, const cpp17_input_iterator& y)
-        {return x.it_ == y.it_;}
-    friend bool operator!=(const cpp17_input_iterator& x, const cpp17_input_iterator& y)
-        {return !(x == y);}
-};
-
-#endif // INPUT_ITERATOR_H
diff --git a/libcxx/test/std/strings/basic.string/string.cons/iter_alloc.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/iter_alloc.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.cons/iter_alloc.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/iter_alloc.pass.cpp
@@ -20,7 +20,7 @@
 
 #include "test_macros.h"
 #include "test_allocator.h"
-#include "../cpp17_input_iterator.h"
+#include "test_iterators.h"
 #include "min_allocator.h"
 
 template <class It>
@@ -34,8 +34,11 @@
     LIBCPP_ASSERT(s2.__invariants());
     assert(s2.size() == static_cast<std::size_t>(std::distance(first, last)));
     unsigned i = 0;
-    for (It it = first; it != last; ++it, ++i)
+    for (It it = first; it != last;) {
         assert(s2[i] == *it);
+        ++it;
+        ++i;
+    }
     assert(s2.get_allocator() == A());
     assert(s2.capacity() >= s2.size());
 }
@@ -50,8 +53,11 @@
     LIBCPP_ASSERT(s2.__invariants());
     assert(s2.size() == static_cast<std::size_t>(std::distance(first, last)));
     unsigned i = 0;
-    for (It it = first; it != last; ++it, ++i)
+    for (It it = first; it != last;) {
         assert(s2[i] == *it);
+        ++it;
+        ++i;
+    }
     assert(s2.get_allocator() == a);
     assert(s2.capacity() >= s2.size());
 }
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
@@ -31,7 +31,6 @@
 
 #include "test_macros.h"
 #include "test_allocator.h"
-#include "../cpp17_input_iterator.h"
 #include "min_allocator.h"
 
 bool test() {
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
@@ -33,7 +33,6 @@
 
 #include "test_macros.h"
 #include "test_allocator.h"
-#include "../cpp17_input_iterator.h"
 #include "min_allocator.h"
 
 bool test() {
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
@@ -37,7 +37,6 @@
 
 #include "test_macros.h"
 #include "test_allocator.h"
-#include "../cpp17_input_iterator.h"
 #include "min_allocator.h"
 
 bool test() {