diff --git a/changelog/15277.bugfix.rst b/changelog/15277.bugfix.rst
new file mode 100644
index 00000000000..ff38059b7a6
--- /dev/null
+++ b/changelog/15277.bugfix.rst
@@ -0,0 +1 @@
+Fixed negative durations being reported for subtests when the clock is mocked or frozen.
diff --git a/testing/test_subtests.py b/testing/test_subtests.py
index f3eab0099c3..3110b22c5e4 100644
--- a/testing/test_subtests.py
+++ b/testing/test_subtests.py
@@ -1147,3 +1147,24 @@ def test(self):
     pytester.syspathinsert()
     result = pytester.runpytest("-n1", "-pxdist.plugin")
     result.assert_outcomes(passed=2)
+
+
+def test_subtest_with_mocked_clock(pytester: pytest.Pytester) -> None:
+    pytester.makepyfile(
+        """
+        import time
+
+        def test_with_subtest(subtests, monkeypatch):
+            real_sleep = time.sleep
+            monkeypatch.setattr(time, "perf_counter", lambda: 0.0)
+            monkeypatch.setattr(time, "time", lambda: 0.0)
+
+            with subtests.test("frozen clock"):
+                real_sleep(0.01)
+        """
+    )
+    result = pytester.runpytest("--junitxml=report.xml")
+    result.assert_outcomes(passed=1)
+
+    xml = pytester.path.joinpath("report.xml").read_text(encoding="utf-8")
+    assert 'time="-' not in xml