Index: libcxx/test/std/containers/sequences/vector/compare.fail.cpp
===================================================================
--- /dev/null
+++ libcxx/test/std/containers/sequences/vector/compare.fail.cpp
@@ -0,0 +1,54 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// <vector>
+
+// bool operator==(const vector& lhs, const vector& rhs);
+// bool operator!=(const vector& lhs, const vector& rhs);
+// bool operator< (const vector& lhs, const vector& rhs);
+// bool operator<=(const vector& lhs, const vector& rhs);
+// bool operator> (const vector& lhs, const vector& rhs);
+// bool operator>=(const vector& lhs, const vector& rhs);
+
+#include <vector>
+
+#include "test_comparisons.h"
+#include "test_macros.h"
+
+int main(int, char**) {
+    {
+        std::vector<LessCompOnly<0>> c;
+        // expected-error@*:* {{invalid operands to binary expression}}
+        TEST_IGNORE_NODISCARD (c == c);
+    }
+    {
+        std::vector<LessCompOnly<1>> c;
+        // expected-error@*:* {{invalid operands to binary expression}}
+        TEST_IGNORE_NODISCARD (c != c);
+    }
+    {
+        std::vector<EqCompOnly<0>> c;
+        // expected-error@*:* {{invalid operands to binary expression}}
+        TEST_IGNORE_NODISCARD (c < c);
+    }
+    {
+        std::vector<EqCompOnly<1>> c;
+        // expected-error@*:* {{invalid operands to binary expression}}
+        TEST_IGNORE_NODISCARD (c <= c);
+    }
+    {
+        std::vector<EqCompOnly<2>> c;
+        // expected-error@*:* {{invalid operands to binary expression}}
+        TEST_IGNORE_NODISCARD (c > c);
+    }
+    {
+        std::vector<EqCompOnly<3>> c;
+        // expected-error@*:* {{invalid operands to binary expression}}
+        TEST_IGNORE_NODISCARD (c >= c);
+    }
+}
Index: libcxx/test/std/containers/sequences/vector/compare.pass.cpp
===================================================================
--- /dev/null
+++ libcxx/test/std/containers/sequences/vector/compare.pass.cpp
@@ -0,0 +1,97 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// <vector>
+
+// bool operator==(const vector& lhs, const vector& rhs);
+// bool operator!=(const vector& lhs, const vector& rhs);
+// bool operator< (const vector& lhs, const vector& rhs);
+// bool operator<=(const vector& lhs, const vector& rhs);
+// bool operator> (const vector& lhs, const vector& rhs);
+// bool operator>=(const vector& lhs, const vector& rhs);
+
+#include <vector>
+#include <cassert>
+
+#include "test_comparisons.h"
+
+int main(int, char**) {
+    {
+        const std::vector<int> c1, c2;
+        assert(testComparisons6(c1, c2, true, false));
+    }
+    {
+        const std::vector<int> c1{1}, c2{2};
+        assert(testComparisons6(c1, c2, false, true));
+    }
+    {
+        const std::vector<int> c1, c2{2};
+        assert(testComparisons6(c1, c2, false, true));
+    }
+    {
+        const std::vector<int> c1{1, 2, 1}, c2{1, 2, 2};
+        assert(testComparisons6(c1, c2, false, true));
+    }
+    {
+        const std::vector<int> c1{3, 2, 3}, c2{3, 1, 3};
+        assert(testComparisons6(c1, c2, false, false));
+    }
+    {
+        const std::vector<int> c1{1, 2}, c2{1, 2, 0};
+        assert(testComparisons6(c1, c2, false, true));
+    }
+    {
+        const std::vector<int> c1{1, 2, 0}, c2{3};
+        assert(testComparisons6(c1, c2, false, true));
+    }
+    {
+        const std::vector<LessAndEqComp> c1, c2;
+        assert(testComparisons6(c1, c2, true, false));
+    }
+    {
+        const std::vector<LessAndEqComp> c1 = {{1, 2}};
+        const std::vector<LessAndEqComp> c2 = {{1, 2}};
+        assert(testComparisons6(c1, c2, true, false));
+    }
+    {
+        const std::vector<LessAndEqComp> c1{{1, 1}}, c2{{1, 2}};
+        assert(testComparisons6(c1, c2, false, true));
+    }
+    {
+        const std::vector<LessAndEqComp> c1, c2{{2, 2}};
+        assert(testComparisons6(c1, c2, false, true));
+    }
+    {
+        const std::vector<LessAndEqComp> c1{{1, 1}, {2, 2}, {2, 0}};
+        const std::vector<LessAndEqComp> c2{{1, 1}, {2, 2}, {1, 0}};
+        assert(testComparisons6(c1, c2, false, false));
+    }
+    {
+        const std::vector<LessAndEqComp> c1{{3, 3}, {3, 3}, {3, 3}};
+        const std::vector<LessAndEqComp> c2{{3, 3}, {2, 2}, {3, 3}};
+        assert(testComparisons6(c1, c2, false, false));
+    }
+    {
+        const std::vector<LessAndEqComp> c1{{1, 1}, {2, 2}};
+        const std::vector<LessAndEqComp> c2{{1, 1}, {2, 2}, {0, 0}};
+        assert(testComparisons6(c1, c2, false, true));
+    }
+    {
+        const std::vector<LessAndEqComp> c1 = {{1, 1}, {2, 2}, {0, 0}};
+        const std::vector<LessAndEqComp> c2 = {{3, 3}};
+        assert(testComparisons6(c1, c2, false, true));
+    }
+    {
+        assert((std::vector<int>() == std::vector<int>()));
+        assert(!(std::vector<int>() != std::vector<int>()));
+        assert(!(std::vector<int>() < std::vector<int>()));
+        assert((std::vector<int>() <= std::vector<int>()));
+        assert(!(std::vector<int>() > std::vector<int>()));
+        assert((std::vector<int>() >= std::vector<int>()));
+    }
+}
Index: libcxx/test/support/test_comparisons.h
===================================================================
--- libcxx/test/support/test_comparisons.h
+++ libcxx/test/support/test_comparisons.h
@@ -19,12 +19,14 @@
 #define TEST_COMPARISONS_H
 
 #include <type_traits>
+#include <cassert>
 #include "test_macros.h"
 
 //  Test all six comparison operations for sanity
 template <class T, class U = T>
 TEST_CONSTEXPR_CXX14 bool testComparisons6(const T& t1, const U& t2, bool isEqual, bool isLess)
 {
+    assert(!(isEqual && isLess) && "isEqual and isLess cannot be both true");
     if (isEqual)
         {
         if (!(t1 == t2)) return false;
@@ -171,4 +173,31 @@
     static_assert((std::is_convertible<decltype(std::declval<const T&>() != std::declval<const U&>()), bool>::value), "");
 }
 
+template <int Dummy>
+struct EqCompOnly {
+  friend bool operator==(const EqCompOnly&, const EqCompOnly&) {
+    return true;
+  }
+};
+
+template <int Dummy>
+struct LessCompOnly {
+  friend bool operator<(const LessCompOnly&, const LessCompOnly&) {
+    return true;
+  }
+};
+
+struct LessAndEqComp {
+  int first;
+  int second;
+
+  friend bool operator<(const LessAndEqComp& lhs, const LessAndEqComp& rhs) {
+    return (lhs.first == rhs.first) ? (lhs.second < rhs.second) : (lhs.first < rhs.first);
+  }
+
+  friend bool operator==(const LessAndEqComp& lhs, const LessAndEqComp& rhs) {
+    return (lhs.first == rhs.first) && (lhs.second == rhs.second);
+  }
+};
+
 #endif // TEST_COMPARISONS_H