diff --git a/run_project_tests.py b/run_project_tests.py
index ab97ca93b..3b0cbeabc 100755
--- a/run_project_tests.py
+++ b/run_project_tests.py
@@ -34,6 +34,7 @@ import tempfile
 import time
 import typing as T
 import xml.etree.ElementTree as ET
+import collections
 
 from mesonbuild import build
 from mesonbuild import environment
@@ -750,14 +751,16 @@ def load_test_json(t: TestDef, stdout_mandatory: bool) -> T.List[TestDef]:
     return all_tests
 
 
-def gather_tests(testdir: Path, stdout_mandatory: bool) -> T.List[TestDef]:
-    tests = [t.name for t in testdir.iterdir() if t.is_dir()]
-    tests = [t for t in tests if not t.startswith('.')]  # Filter non-tests files (dot files, etc)
-    test_defs = [TestDef(testdir / t, None, []) for t in tests]
+def gather_tests(testdir: Path, stdout_mandatory: bool, only: T.List[str]) -> T.List[TestDef]:
     all_tests: T.List[TestDef] = []
-    for t in test_defs:
-        all_tests.extend(load_test_json(t, stdout_mandatory))
-
+    for t in testdir.iterdir():
+        # Filter non-tests files (dot files, etc)
+        if not t.is_dir() or t.name.startswith('.'):
+            continue
+        if only and not any(t.name.startswith(prefix) for prefix in only):
+            continue
+        test_def = TestDef(t, None, [])
+        all_tests.extend(load_test_json(test_def, stdout_mandatory))
     return sorted(all_tests)
 
 
@@ -937,11 +940,11 @@ def should_skip_rust(backend: Backend) -> bool:
         return True
     return False
 
-def detect_tests_to_run(only: T.List[str], use_tmp: bool) -> T.List[T.Tuple[str, T.List[TestDef], bool]]:
+def detect_tests_to_run(only: T.Dict[str, T.List[str]], use_tmp: bool) -> T.List[T.Tuple[str, T.List[TestDef], bool]]:
     """
     Parameters
     ----------
-    only: list of str, optional
+    only: dict of categories and list of test cases, optional
         specify names of tests to run
 
     Returns
@@ -997,9 +1000,9 @@ def detect_tests_to_run(only: T.List[str], use_tmp: bool) -> T.List[T.Tuple[str,
     assert categories == ALL_TESTS, 'argparse("--only", choices=ALL_TESTS) need to be updated to match all_tests categories'
 
     if only:
-        all_tests = [t for t in all_tests if t.category in only]
+        all_tests = [t for t in all_tests if t.category in only.keys()]
 
-    gathered_tests = [(t.category, gather_tests(Path('test cases', t.subdir), t.stdout_mandatory), t.skip) for t in all_tests]
+    gathered_tests = [(t.category, gather_tests(Path('test cases', t.subdir), t.stdout_mandatory, only[t.category]), t.skip) for t in all_tests]
     return gathered_tests
 
 def run_tests(all_tests: T.List[T.Tuple[str, T.List[TestDef], bool]],
@@ -1323,7 +1326,8 @@ if __name__ == '__main__':
                         help='Stop running if test case fails')
     parser.add_argument('--no-unittests', action='store_true',
                         help='Not used, only here to simplify run_tests.py')
-    parser.add_argument('--only', help='name of test(s) to run', nargs='+', choices=ALL_TESTS)
+    parser.add_argument('--only', default=[],
+                        help='name of test(s) to run, in format "category[/name]" where category is one of: ' + ', '.join(ALL_TESTS), nargs='+')
     parser.add_argument('--cross-file', action='store', help='File describing cross compilation environment.')
     parser.add_argument('--native-file', action='store', help='File describing native compilation environment.')
     parser.add_argument('--use-tmpdir', action='store_true', help='Use tmp directory for temporary files.')
@@ -1348,8 +1352,15 @@ if __name__ == '__main__':
         os.chdir(script_dir)
     check_format()
     check_meson_commands_work(options)
+    only = collections.defaultdict(list)
+    for i in options.only:
+        try:
+            cat, case = i.split('/')
+            only[cat].append(case)
+        except ValueError:
+            only[i].append('')
     try:
-        all_tests = detect_tests_to_run(options.only, options.use_tmpdir)
+        all_tests = detect_tests_to_run(only, options.use_tmpdir)
         (passing_tests, failing_tests, skipped_tests) = run_tests(all_tests, 'meson-test-run', options.failfast, options.extra_args, options.use_tmpdir)
     except StopException:
         pass