diff --git a/libcxx/cmake/caches/Generic-debug-iterators.cmake b/libcxx/cmake/caches/Generic-debug-iterators.cmake
new file mode 100644
--- /dev/null
+++ b/libcxx/cmake/caches/Generic-debug-iterators.cmake
@@ -0,0 +1,2 @@
+set(LIBCXX_TEST_PARAMS "debug_level=1" "additional_features=LIBCXX-DEBUG-FIXME" CACHE STRING "")
+set(LIBCXXABI_TEST_PARAMS "${LIBCXX_TEST_PARAMS}" CACHE STRING "")
diff --git a/libcxx/test/libcxx/containers/sequences/vector/robust_against_adl.pass.cpp b/libcxx/test/libcxx/containers/sequences/vector/robust_against_adl.pass.cpp
--- a/libcxx/test/libcxx/containers/sequences/vector/robust_against_adl.pass.cpp
+++ b/libcxx/test/libcxx/containers/sequences/vector/robust_against_adl.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03
+// UNSUPPORTED: debug_level=0, debug_level=1
 
 // <vector>
 
diff --git a/libcxx/test/std/algorithms/alg.sorting/alg.merge/inplace_merge_comp.pass.cpp b/libcxx/test/std/algorithms/alg.sorting/alg.merge/inplace_merge_comp.pass.cpp
--- a/libcxx/test/std/algorithms/alg.sorting/alg.merge/inplace_merge_comp.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.sorting/alg.merge/inplace_merge_comp.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// XFAIL: LIBCXX-DEBUG-FIXME
+
 // <algorithm>
 
 // template<BidirectionalIterator Iter, StrictWeakOrder<auto, Iter::value_type> Compare>
diff --git a/libcxx/test/std/containers/unord/unord.set/insert_hint_const_lvalue.pass.cpp b/libcxx/test/std/containers/unord/unord.set/insert_hint_const_lvalue.pass.cpp
--- a/libcxx/test/std/containers/unord/unord.set/insert_hint_const_lvalue.pass.cpp
+++ b/libcxx/test/std/containers/unord/unord.set/insert_hint_const_lvalue.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// UNSUPPORTED: LIBCXX-DEBUG-FIXME
+
 // <unordered_set>
 
 // template <class Value, class Hash = hash<Value>, class Pred = equal_to<Value>,
diff --git a/libcxx/test/std/containers/views/span.cons/deduct.pass.cpp b/libcxx/test/std/containers/views/span.cons/deduct.pass.cpp
--- a/libcxx/test/std/containers/views/span.cons/deduct.pass.cpp
+++ b/libcxx/test/std/containers/views/span.cons/deduct.pass.cpp
@@ -7,6 +7,7 @@
 //
 //===---------------------------------------------------------------------===//
 // UNSUPPORTED: c++03, c++11, c++14, c++17
+// XFAIL: LIBCXX-DEBUG-FIXME
 
 // <span>
 
diff --git a/libcxx/test/std/containers/views/span.iterators/begin.pass.cpp b/libcxx/test/std/containers/views/span.iterators/begin.pass.cpp
--- a/libcxx/test/std/containers/views/span.iterators/begin.pass.cpp
+++ b/libcxx/test/std/containers/views/span.iterators/begin.pass.cpp
@@ -6,6 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 // UNSUPPORTED: c++03, c++11, c++14, c++17
+// XFAIL: LIBCXX-DEBUG-FIXME
 
 // <span>
 
diff --git a/libcxx/test/std/containers/views/span.iterators/end.pass.cpp b/libcxx/test/std/containers/views/span.iterators/end.pass.cpp
--- a/libcxx/test/std/containers/views/span.iterators/end.pass.cpp
+++ b/libcxx/test/std/containers/views/span.iterators/end.pass.cpp
@@ -6,6 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 // UNSUPPORTED: c++03, c++11, c++14, c++17
+// XFAIL: LIBCXX-DEBUG-FIXME
 
 // <span>
 
diff --git a/libcxx/test/std/containers/views/span.iterators/rbegin.pass.cpp b/libcxx/test/std/containers/views/span.iterators/rbegin.pass.cpp
--- a/libcxx/test/std/containers/views/span.iterators/rbegin.pass.cpp
+++ b/libcxx/test/std/containers/views/span.iterators/rbegin.pass.cpp
@@ -6,6 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 // UNSUPPORTED: c++03, c++11, c++14, c++17
+// XFAIL: LIBCXX-DEBUG-FIXME
 
 // <span>
 
diff --git a/libcxx/test/std/containers/views/span.iterators/rend.pass.cpp b/libcxx/test/std/containers/views/span.iterators/rend.pass.cpp
--- a/libcxx/test/std/containers/views/span.iterators/rend.pass.cpp
+++ b/libcxx/test/std/containers/views/span.iterators/rend.pass.cpp
@@ -6,6 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 // UNSUPPORTED: c++03, c++11, c++14, c++17
+// XFAIL: LIBCXX-DEBUG-FIXME
 
 // <span>
 
diff --git a/libcxx/test/std/containers/views/span.sub/first.pass.cpp b/libcxx/test/std/containers/views/span.sub/first.pass.cpp
--- a/libcxx/test/std/containers/views/span.sub/first.pass.cpp
+++ b/libcxx/test/std/containers/views/span.sub/first.pass.cpp
@@ -7,6 +7,7 @@
 //
 //===---------------------------------------------------------------------===//
 // UNSUPPORTED: c++03, c++11, c++14, c++17
+// XFAIL: LIBCXX-DEBUG-FIXME
 
 // <span>
 
diff --git a/libcxx/test/std/containers/views/span.sub/last.pass.cpp b/libcxx/test/std/containers/views/span.sub/last.pass.cpp
--- a/libcxx/test/std/containers/views/span.sub/last.pass.cpp
+++ b/libcxx/test/std/containers/views/span.sub/last.pass.cpp
@@ -7,6 +7,7 @@
 //
 //===---------------------------------------------------------------------===//
 // UNSUPPORTED: c++03, c++11, c++14, c++17
+// XFAIL: LIBCXX-DEBUG-FIXME
 
 // <span>
 
diff --git a/libcxx/test/std/containers/views/span.sub/subspan.pass.cpp b/libcxx/test/std/containers/views/span.sub/subspan.pass.cpp
--- a/libcxx/test/std/containers/views/span.sub/subspan.pass.cpp
+++ b/libcxx/test/std/containers/views/span.sub/subspan.pass.cpp
@@ -7,6 +7,7 @@
 //
 //===---------------------------------------------------------------------===//
 // UNSUPPORTED: c++03, c++11, c++14, c++17
+// XFAIL: LIBCXX-DEBUG-FIXME
 
 // <span>
 
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/path.factory.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/path.factory.pass.cpp
--- a/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/path.factory.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/path.factory.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// XFAIL: LIBCXX-DEBUG-FIXME
+
 // UNSUPPORTED: c++03
 // ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_DISABLE_DEPRECATION_WARNINGS
 
diff --git a/libcxx/test/std/input.output/filesystems/fs.op.funcs/fs.op.proximate/proximate.pass.cpp b/libcxx/test/std/input.output/filesystems/fs.op.funcs/fs.op.proximate/proximate.pass.cpp
--- a/libcxx/test/std/input.output/filesystems/fs.op.funcs/fs.op.proximate/proximate.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/fs.op.funcs/fs.op.proximate/proximate.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// XFAIL: LIBCXX-DEBUG-FIXME
+
 // UNSUPPORTED: c++03
 
 // <filesystem>
diff --git a/libcxx/test/std/iterators/iterator.primitives/iterator.operations/robust_against_adl.pass.cpp b/libcxx/test/std/iterators/iterator.primitives/iterator.operations/robust_against_adl.pass.cpp
--- a/libcxx/test/std/iterators/iterator.primitives/iterator.operations/robust_against_adl.pass.cpp
+++ b/libcxx/test/std/iterators/iterator.primitives/iterator.operations/robust_against_adl.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// XFAIL: LIBCXX-DEBUG-FIXME
+
 // <iterator>
 
 #include <iterator>
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/iterator.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/iterator.pass.cpp
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/iterator.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/iterator.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// XFAIL: LIBCXX-DEBUG-FIXME
+
 // <string>
 
 // template<class InputIterator>
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/copy.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/copy.pass.cpp
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/copy.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/copy.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: clang-8
+// UNSUPPORTED: LIBCXX-DEBUG-FIXME
 
 // <string>
 
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/copy.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/copy.pass.cpp
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/copy.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/copy.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// UNSUPPORTED: LIBCXX-DEBUG-FIXME
+
 // <string>
 
 // template<> struct char_traits<char16_t>
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/copy.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/copy.pass.cpp
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/copy.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/copy.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// UNSUPPORTED: LIBCXX-DEBUG-FIXME
+
 // <string>
 
 // template<> struct char_traits<char32_t>
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/copy.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/copy.pass.cpp
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/copy.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/copy.pass.cpp
@@ -8,6 +8,7 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: clang-8
+// UNSUPPORTED: LIBCXX-DEBUG-FIXME
 
 // <string>
 
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/copy.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/copy.pass.cpp
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/copy.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/copy.pass.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: clang-8
+// UNSUPPORTED: LIBCXX-DEBUG-FIXME
 
 // <string>
 
diff --git a/libcxx/test/std/strings/string.view/string.view.ops/copy.pass.cpp b/libcxx/test/std/strings/string.view/string.view.ops/copy.pass.cpp
--- a/libcxx/test/std/strings/string.view/string.view.ops/copy.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.ops/copy.pass.cpp
@@ -8,6 +8,7 @@
 
 // XFAIL: gcc-10
 //     GCC's __builtin_strlen isn't constexpr yet
+// UNSUPPORTED: LIBCXX-DEBUG-FIXME
 
 // <string_view>
 
diff --git a/libcxx/utils/ci/buildkite-pipeline.yml b/libcxx/utils/ci/buildkite-pipeline.yml
--- a/libcxx/utils/ci/buildkite-pipeline.yml
+++ b/libcxx/utils/ci/buildkite-pipeline.yml
@@ -125,6 +125,18 @@
         - exit_status: -1  # Agent was lost
           limit: 2
 
+  - label: "Debug iterators"
+    command: "libcxx/utils/ci/run-buildbot generic-debug-iterators"
+    artifact_paths:
+      - "**/test-results.xml"
+      - "**/*.abilist"
+    agents:
+      queue: "libcxx-builders"
+    retry:
+      automatic:
+        - exit_status: -1  # Agent was lost
+          limit: 2
+
   - label: "GCC/C++20"
     command: "libcxx/utils/ci/run-buildbot generic-gcc"
     artifact_paths:
diff --git a/libcxx/utils/ci/run-buildbot b/libcxx/utils/ci/run-buildbot
--- a/libcxx/utils/ci/run-buildbot
+++ b/libcxx/utils/ci/run-buildbot
@@ -202,6 +202,14 @@
     check-cxx-cxxabi
     check-abi-list
 ;;
+generic-debug-iterators)
+    export CC=clang-tot
+    export CXX=clang++-tot
+    clean
+    generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-debug-iterators.cmake"
+    check-cxx-cxxabi
+    check-abi-list
+;;
 generic-noexceptions)
     export CC=clang
     export CXX=clang++