diff --git a/libcxx/test/libcxx/gdb/gdb_pretty_printer_test.sh.cpp b/libcxx/test/libcxx/gdb/gdb_pretty_printer_test.sh.cpp
--- a/libcxx/test/libcxx/gdb/gdb_pretty_printer_test.sh.cpp
+++ b/libcxx/test/libcxx/gdb/gdb_pretty_printer_test.sh.cpp
@@ -659,6 +659,7 @@
   string_test();
   a_namespace::string_view_test();
 
+  u16string_test();
   u32string_test();
   tuple_test();
   unique_ptr_test();
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
@@ -18,590 +18,12 @@
 #
 
 steps:
-  #
-  # Light pre-commit tests for things like formatting or when people forget
-  # to update generated files.
-  #
-  - label: "Format"
-    command: "libcxx/utils/ci/run-buildbot check-format"
-    artifact_paths:
-      - "**/clang-format.patch"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    soft_fail:
-        - exit_status: 1
-    timeout_in_minutes: 120
-
-  - label: "Generated output"
-    command: "libcxx/utils/ci/run-buildbot check-generated-output"
-    artifact_paths:
-      - "**/generated_output.patch"
-      - "**/generated_output.status"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  #
-  # General testing with the default configuration, under all the supported
-  # Standard modes, with Clang and GCC. This catches most issues upfront.
-  # The goal of this step is to catch most issues while being very fast.
-  #
-  - wait
-
-  - label: "C++2b"
-    command: "libcxx/utils/ci/run-buildbot generic-cxx2b"
-    artifact_paths:
-      - "**/test-results.xml"
-      - "**/*.abilist"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "C++20"
-    command: "libcxx/utils/ci/run-buildbot generic-cxx20"
-    artifact_paths:
-      - "**/test-results.xml"
-      - "**/*.abilist"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "C++17"
-    command: "libcxx/utils/ci/run-buildbot generic-cxx17"
-    artifact_paths:
-      - "**/test-results.xml"
-      - "**/*.abilist"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "C++14"
-    command: "libcxx/utils/ci/run-buildbot generic-cxx14"
-    artifact_paths:
-      - "**/test-results.xml"
-      - "**/*.abilist"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-  - label: "C++11"
-    command: "libcxx/utils/ci/run-buildbot generic-cxx11"
-    artifact_paths:
-      - "**/test-results.xml"
-      - "**/*.abilist"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "C++03"
-    command: "libcxx/utils/ci/run-buildbot generic-cxx03"
-    artifact_paths:
-      - "**/test-results.xml"
-      - "**/*.abilist"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "GCC 11 / C++latest"
-    command: "libcxx/utils/ci/run-buildbot generic-gcc"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  #
-  # All other supported configurations of libc++.
-  #
-  - wait
-
-  - label: "GCC 11 / C++11"
-    command: "libcxx/utils/ci/run-buildbot generic-gcc-cxx11"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "Clang 11"
-    command: "libcxx/utils/ci/run-buildbot generic-clang-11"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "Clang 12"
-    command: "libcxx/utils/ci/run-buildbot generic-clang-12"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "-fno-exceptions"
-    command: "libcxx/utils/ci/run-buildbot generic-noexceptions"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "Modular build"
-    command: "libcxx/utils/ci/run-buildbot generic-modules"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "Static libraries"
-    command: "libcxx/utils/ci/run-buildbot generic-static"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "Assertions enabled"
-    command: "libcxx/utils/ci/run-buildbot generic-assertions"
-    artifact_paths:
-      - "**/test-results.xml"
-      - "**/*.abilist"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "Debug iterators"
-    command: "libcxx/utils/ci/run-buildbot generic-debug-iterators"
-    artifact_paths:
-      - "**/test-results.xml"
-      - "**/*.abilist"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "ASAN"
-    command: "libcxx/utils/ci/run-buildbot generic-asan"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "TSAN"
-    command: "libcxx/utils/ci/run-buildbot generic-tsan"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "UBSAN"
-    command: "libcxx/utils/ci/run-buildbot generic-ubsan"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "With LLVM's libunwind"
-    command: "libcxx/utils/ci/run-buildbot generic-with_llvm_unwinder"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "Single-threaded"
-    command: "libcxx/utils/ci/run-buildbot generic-singlethreaded"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "No debug mode"
-    command: "libcxx/utils/ci/run-buildbot generic-no-debug"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "No Filesystem"
-    command: "libcxx/utils/ci/run-buildbot generic-no-filesystem"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "No random device"
-    command: "libcxx/utils/ci/run-buildbot generic-no-random_device"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "No locale"
-    command: "libcxx/utils/ci/run-buildbot generic-no-localization"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "No Unicode"
-    command: "libcxx/utils/ci/run-buildbot generic-no-unicode"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "Benchmarks"
-    command: "libcxx/utils/ci/run-buildbot benchmarks"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "Documentation"
-    command: "libcxx/utils/ci/run-buildbot documentation"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "Legacy Lit configuration"
-    command: "libcxx/utils/ci/run-buildbot legacy-test-config"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "Legacy standalone build"
-    command: "libcxx/utils/ci/run-buildbot legacy-standalone"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "Unified standalone build"
-    command: "libcxx/utils/ci/run-buildbot unified-standalone"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "Runtimes build"
-    command: "libcxx/utils/ci/run-buildbot runtimes-build"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "Windows (DLL)"
-    command: "bash libcxx/utils/ci/run-buildbot windows-dll"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "windows"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "Windows (Static)"
-    command: "bash libcxx/utils/ci/run-buildbot windows-static"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "windows"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "32 bit"
-    command: "libcxx/utils/ci/run-buildbot generic-32bit"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "linux"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "MacOS x86_64"
-    command: "libcxx/utils/ci/run-buildbot generic-cxx20"
-    artifact_paths:
-      - "**/test-results.xml"
-      - "**/*.abilist"
-    agents:
-      queue: "libcxx-builders"
-      os: "macos"
-      arch: "x86_64"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "MacOS arm64"
-    command: "libcxx/utils/ci/run-buildbot generic-cxx20"
-    artifact_paths:
-      - "**/test-results.xml"
-      - "**/*.abilist"
-    agents:
-      queue: "libcxx-builders"
-      os: "macos"
-      arch: "arm64"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  # Build with the configuration we use to generate libc++.dylib on Apple platforms
-  - label: "Apple system"
-    command: "libcxx/utils/ci/run-buildbot x86_64-apple-system"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "macos"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "Apple system -fno-exceptions"
-    command: "libcxx/utils/ci/run-buildbot x86_64-apple-system-noexceptions"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "macos"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  # Test back-deployment to older Apple platforms
-  - label: "Apple back-deployment macosx10.9"
-    command: "libcxx/utils/ci/run-buildbot x86_64-apple-system-backdeployment-10.9"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "macos10.15" # TODO: For now, we're running the back-deployment tests for 10.9 on 10.15, because we don't have proper 10.9 machines
-      arch: "x86_64"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
-  - label: "Apple back-deployment macosx10.15"
-    command: "libcxx/utils/ci/run-buildbot x86_64-apple-system-backdeployment-10.15"
-    artifact_paths:
-      - "**/test-results.xml"
-    agents:
-      queue: "libcxx-builders"
-      os: "macos10.15"
-      arch: "x86_64"
-    retry:
-      automatic:
-        - exit_status: -1  # Agent was lost
-          limit: 2
-    timeout_in_minutes: 120
-
   - label: "AArch64"
     command: "libcxx/utils/ci/run-buildbot aarch64"
     artifact_paths:
       - "**/test-results.xml"
     agents:
-      queue: "libcxx-builders-linaro-arm"
+      queue: "libcxx-builders-linaro-arm-test"
       arch: "aarch64"
     retry:
       automatic:
@@ -614,7 +36,7 @@
     artifact_paths:
       - "**/test-results.xml"
     agents:
-      queue: "libcxx-builders-linaro-arm"
+      queue: "libcxx-builders-linaro-arm-test"
       arch: "aarch64"
     retry:
       automatic:
@@ -627,7 +49,7 @@
     artifact_paths:
       - "**/test-results.xml"
     agents:
-      queue: "libcxx-builders-linaro-arm"
+      queue: "libcxx-builders-linaro-arm-test"
       arch: "armv8l"
     retry:
       automatic:
@@ -640,7 +62,7 @@
     artifact_paths:
       - "**/test-results.xml"
     agents:
-      queue: "libcxx-builders-linaro-arm"
+      queue: "libcxx-builders-linaro-arm-test"
       arch: "armv8l"
     retry:
       automatic:
@@ -653,7 +75,7 @@
     artifact_paths:
       - "**/test-results.xml"
     agents:
-      queue: "libcxx-builders-linaro-arm"
+      queue: "libcxx-builders-linaro-arm-test"
       arch: "armv8l" # Compiling for v7, running on v8 hardware
     retry:
       automatic:
@@ -666,7 +88,7 @@
     artifact_paths:
       - "**/test-results.xml"
     agents:
-      queue: "libcxx-builders-linaro-arm"
+      queue: "libcxx-builders-linaro-arm-test"
       arch: "armv8l" # Compiling for v7, running on v8 hardware
     retry:
       automatic: