diff --git a/src/collective/comm.cc b/src/collective/comm.cc
index 9ee1e0e6a..3c49303fa 100644
--- a/src/collective/comm.cc
+++ b/src/collective/comm.cc
@@ -23,7 +23,7 @@ Comm::Comm(std::string const& host, std::int32_t port, std::chrono::seconds time
       retry_{retry},
       tracker_{host, port, -1},
       task_id_{std::move(task_id)},
-      loop_{std::make_shared<Loop>(timeout)} {}
+      loop_{std::shared_ptr<Loop>{new Loop{timeout}}} {}
 
 Result ConnectTrackerImpl(proto::PeerInfo info, std::chrono::seconds timeout, std::int32_t retry,
                           std::string const& task_id, TCPSocket* out, std::int32_t rank,
diff --git a/tests/buildkite/pipeline-mac-m1.yml b/tests/buildkite/pipeline-mac-m1.yml
new file mode 100644
index 000000000..7e4a664ac
--- /dev/null
+++ b/tests/buildkite/pipeline-mac-m1.yml
@@ -0,0 +1,8 @@
+steps:
+  - block: ":rocket: Run this test job"
+    if: build.pull_request.id != null || build.branch =~ /^dependabot\//
+  - label: ":macos: Build and Test XGBoost for MacOS M1 with Clang 11"
+    command: "tests/buildkite/test-macos-m1-clang11.sh"
+    key: mac-m1-appleclang11
+    agents:
+      queue: mac-mini-m1
diff --git a/tests/buildkite/test-macos-m1-clang11.sh b/tests/buildkite/test-macos-m1-clang11.sh
new file mode 100755
index 000000000..fdd1aba84
--- /dev/null
+++ b/tests/buildkite/test-macos-m1-clang11.sh
@@ -0,0 +1,33 @@
+#!/bin/bash
+
+set -euo pipefail
+
+source tests/buildkite/conftest.sh
+
+# Display system info
+echo "--- Display system information"
+set -x
+system_profiler SPSoftwareDataType
+sysctl -n machdep.cpu.brand_string
+uname -m
+set +x
+
+# Create new Conda env
+echo "--- Set up Conda env"
+. $HOME/mambaforge/etc/profile.d/conda.sh
+. $HOME/mambaforge/etc/profile.d/mamba.sh
+conda_env=xgboost_dev_$(uuidgen | tr '[:upper:]' '[:lower:]' | tr -d '-')
+mamba create -y -n ${conda_env} python=3.8
+conda activate ${conda_env}
+mamba env update -n ${conda_env} --file tests/ci_build/conda_env/macos_cpu_test.yml
+
+# Ensure that XGBoost can be built with Clang 11
+echo "--- Build and Test XGBoost with MacOS M1, Clang 11"
+set -x
+LLVM11_PATH=$(brew --prefix llvm\@11)
+mkdir build
+pushd build
+cmake .. -GNinja -DCMAKE_C_COMPILER=${LLVM11_PATH}/bin/clang \
+  -DCMAKE_CXX_COMPILER=${LLVM11_PATH}/bin/clang++ -DGOOGLE_TEST=ON \
+  -DUSE_DMLC_GTEST=ON
+ninja -v
diff --git a/tests/ci_build/conda_env/macos_cpu_test.yml b/tests/ci_build/conda_env/macos_cpu_test.yml
index dfc1ee600..ce9ca4b1b 100644
--- a/tests/ci_build/conda_env/macos_cpu_test.yml
+++ b/tests/ci_build/conda_env/macos_cpu_test.yml
@@ -32,11 +32,10 @@ dependencies:
 - jsonschema
 - boto3
 - awscli
-- py-ubjson
 - cffi
 - pyarrow
 - pyspark>=3.4.0
 - cloudpickle
 - pip:
   - sphinx_rtd_theme
-  - datatable
+  - py-ubjson
diff --git a/tests/cpp/collective/test_allreduce.cc b/tests/cpp/collective/test_allreduce.cc
index 50b1722ae..77d23f6fe 100644
--- a/tests/cpp/collective/test_allreduce.cc
+++ b/tests/cpp/collective/test_allreduce.cc
@@ -53,7 +53,7 @@ class AllreduceWorker : public WorkerForTest {
     Context ctx;
     std::vector<std::uint32_t> data(comm_.World(), 0);
     data[comm_.Rank()] = ~std::uint32_t{0};
-    auto pcoll = std::make_shared<Coll>();
+    auto pcoll = std::shared_ptr<Coll>{new Coll{}};
     auto rc = pcoll->Allreduce(&ctx, comm_, EraseType(common::Span{data.data(), data.size()}),
                                ArrayInterfaceHandler::kU4, Op::kBitwiseOR);
     ASSERT_TRUE(rc.OK()) << rc.Report();
diff --git a/tests/cpp/collective/test_loop.cc b/tests/cpp/collective/test_loop.cc
index 4686060ce..e5ef987f3 100644
--- a/tests/cpp/collective/test_loop.cc
+++ b/tests/cpp/collective/test_loop.cc
@@ -41,7 +41,7 @@ class LoopTest : public ::testing::Test {
     rc = pair_.first.NonBlocking(true);
     ASSERT_TRUE(rc.OK());
 
-    loop_ = std::make_shared<Loop>(timeout);
+    loop_ = std::shared_ptr<Loop>{new Loop{timeout}};
   }
 
   void TearDown() override {