diff --git a/bazel/resmoke/BUILD.bazel b/bazel/resmoke/BUILD.bazel
index 165044c5221..7a026a7cc8e 100644
--- a/bazel/resmoke/BUILD.bazel
+++ b/bazel/resmoke/BUILD.bazel
@@ -64,6 +64,17 @@ genrule(
     visibility = ["//visibility:public"],
 )
 
+genrule(
+    name = "all_ifr_flags",
+    srcs = [],
+    outs = ["all_ifr_flags.txt"],
+    cmd = """
+    awk '/^STABLE_all_ifr_flags/ { for (i=2; i<=NF; i++) print $$i }' bazel-out/stable-status.txt > $@
+    """,
+    stamp = True,
+    visibility = ["//visibility:public"],
+)
+
 # We want to use keys from volatile-status in the resmoke `py_test`, so this creates a file that
 # it can depend on.
 genrule(
diff --git a/bazel/resmoke/resmoke.bzl b/bazel/resmoke/resmoke.bzl
index a80a2f43810..56d6f10aa0d 100644
--- a/bazel/resmoke/resmoke.bzl
+++ b/bazel/resmoke/resmoke.bzl
@@ -227,6 +227,7 @@ def resmoke_suite_test(
         "//bazel/resmoke:on_feature_flags",
         "//bazel/resmoke:off_feature_flags",
         "//bazel/resmoke:unreleased_ifr_flags",
+        "//bazel/resmoke:all_ifr_flags",
         "//bazel/resmoke:volatile_status",
         "//bazel/resmoke:resource_monitor",
         ":%s" % historic_runtimes,
diff --git a/bazel/workspace_status.py b/bazel/workspace_status.py
index 6c2e7ce6457..6e3e55b0c07 100644
--- a/bazel/workspace_status.py
+++ b/bazel/workspace_status.py
@@ -60,6 +60,13 @@ def print_feature_flag_status():
     ]
     print_stable_key("unreleased_ifr_flags", " ".join(unreleased_ifr_flags))
 
+    all_ifr_flags = [
+        name
+        for name, flag in all_flags.items()
+        if idl_binder.is_incremental_feature_rollout_flag(flag)
+    ]
+    print_stable_key("all_ifr_flags", " ".join(all_ifr_flags))
+
 
 def print_evergreen_expansions():
     for expansion in [
diff --git a/buildscripts/idl/gen_all_feature_flag_list.py b/buildscripts/idl/gen_all_feature_flag_list.py
index 81b8a5ae1b4..14e404fe6b4 100755
--- a/buildscripts/idl/gen_all_feature_flag_list.py
+++ b/buildscripts/idl/gen_all_feature_flag_list.py
@@ -87,6 +87,15 @@ def get_all_unreleased_ifr_feature_flags(idl_dirs: list[str] = DEFAULT_IDL_DIRS)
     ]
 
 
+def get_all_ifr_feature_flags(idl_dirs: list[str] = DEFAULT_IDL_DIRS):
+    """Generate a list of all IFR feature flags regardless of phase."""
+    all_flags = lib.get_all_feature_flags(idl_dirs)
+
+    return [
+        name for name, flag in all_flags.items() if binder.is_incremental_feature_rollout_flag(flag)
+    ]
+
+
 def write_feature_flags_to_file(flags: list[str], filename: str):
     """Helper function to write feature flags to a file."""
     with open(filename, "w") as output_file:
diff --git a/buildscripts/idl/idl/binder.py b/buildscripts/idl/idl/binder.py
index dec3537a8f9..035b720c509 100644
--- a/buildscripts/idl/idl/binder.py
+++ b/buildscripts/idl/idl/binder.py
@@ -1929,6 +1929,18 @@ def is_unreleased_incremental_rollout_feature_flag(feature_flag):
     )
 
 
+def is_incremental_feature_rollout_flag(feature_flag):
+    """Determine if an idl.FeatureFlag is an Incremental Feature Rollout (IFR) flag
+    in any phase (in_development, rollout, or released) without validating its syntax.
+    """
+    # type: (syntax.FeatureFlag) -> bool
+
+    if not feature_flag.incremental_rollout_phase:
+        return False
+    phase = ast.FeatureFlagRolloutPhase.bind(feature_flag.incremental_rollout_phase)
+    return phase is not None and phase != ast.FeatureFlagRolloutPhase.NOT_FOR_INCREMENTAL_ROLLOUT
+
+
 def bind(parsed_spec):
     # type: (syntax.IDLSpec) -> ast.IDLBoundSpec
     """Read an idl.syntax, create an idl.ast tree, and validate the final IDL Specification."""
diff --git a/buildscripts/resmokeconfig/feature_flag_test.idl b/buildscripts/resmokeconfig/feature_flag_test.idl
index bbe0cdacdda..72d00765907 100644
--- a/buildscripts/resmokeconfig/feature_flag_test.idl
+++ b/buildscripts/resmokeconfig/feature_flag_test.idl
@@ -6,3 +6,14 @@ feature_flags:
         cpp_varname: gFeatureFlagToaster
         default: false
         fcv_gated: true
+    featureFlagTestIFR:
+        description: "IFR feature flag used by fixture builder unit tests"
+        cpp_varname: gFeatureFlagTestIFR
+        default: false
+        fcv_gated: false
+        incremental_rollout_phase: in_development
+    featureFlagTestNonIFR:
+        description: "Non-IFR feature flag used by fixture builder unit tests"
+        cpp_varname: gFeatureFlagTestNonIFR
+        default: false
+        fcv_gated: false
diff --git a/buildscripts/resmokelib/config.py b/buildscripts/resmokelib/config.py
index c6b2611958f..c34f43c83bd 100644
--- a/buildscripts/resmokelib/config.py
+++ b/buildscripts/resmokelib/config.py
@@ -584,6 +584,10 @@ DISABLED_FEATURE_FLAGS = None
 # List of feature flags to enable.
 ENABLED_FEATURE_FLAGS = []
 
+# Set of all IFR (Incremental Feature Rollout) feature flag names, used to filter
+# IFR flags from injection in multiversion fixtures.
+IFR_FEATURE_FLAGS = None
+
 # The path to the mongo executable used by resmoke.py.
 MONGO_EXECUTABLE = None
 
diff --git a/buildscripts/resmokelib/configure_resmoke.py b/buildscripts/resmokelib/configure_resmoke.py
index 570b7a9569a..17f931df3f3 100644
--- a/buildscripts/resmokelib/configure_resmoke.py
+++ b/buildscripts/resmokelib/configure_resmoke.py
@@ -44,6 +44,7 @@ BASE_16_TO_INT = 16
 COLLECTOR_ENDPOINT = "otel-collector.prod.corp.mongodb.com:443"
 BAZEL_GENERATED_OFF_FEATURE_FLAGS = "bazel/resmoke/off_feature_flags.txt"
 BAZEL_GENERATED_UNRELEASED_IFR_FEATURE_FLAGS = "bazel/resmoke/unreleased_ifr_feature_flags.txt"
+BAZEL_GENERATED_ALL_IFR_FEATURE_FLAGS = "bazel/resmoke/all_ifr_flags.txt"
 EVERGREEN_EXPANSIONS_FILE = "../expansions.yml"
 
 
@@ -562,11 +563,17 @@ flags in common: {common_set}
             (default_disabled_set | disabled_feature_flags_set) - enabled_feature_flags_set
         )
 
+        if os.path.exists(BAZEL_GENERATED_ALL_IFR_FEATURE_FLAGS):
+            all_ifr_set = set(process_feature_flag_file(BAZEL_GENERATED_ALL_IFR_FEATURE_FLAGS))
+        else:
+            all_ifr_set = set(gen_all_feature_flag_list.get_all_ifr_feature_flags())
+
         return (
             list(enabled_feature_flags_set),
             list(disabled_feature_flags_set),
             default_disabled_feature_flags,
             off_feature_flags,
+            all_ifr_set,
         )
 
     _config.RUN_ALL_FEATURE_FLAG_TESTS = config.pop("run_all_feature_flag_tests")
@@ -575,6 +582,7 @@ flags in common: {common_set}
     _config.ADDITIONAL_FEATURE_FLAGS_FILE = config.pop("additional_feature_flags_file")
     _config.ENABLED_FEATURE_FLAGS = []
     _config.DISABLED_FEATURE_FLAGS = []
+    _config.IFR_FEATURE_FLAGS = None
     default_disabled_feature_flags = []
     off_feature_flags = []
     if values["command"] == "run":
@@ -583,6 +591,7 @@ flags in common: {common_set}
             _config.DISABLED_FEATURE_FLAGS,
             default_disabled_feature_flags,
             off_feature_flags,
+            _config.IFR_FEATURE_FLAGS,
         ) = set_up_feature_flags()
     else:
         # Explicitly ignore these run-related options.
diff --git a/buildscripts/resmokelib/core/programs.py b/buildscripts/resmokelib/core/programs.py
index c8bbd86a491..8964dc80a36 100644
--- a/buildscripts/resmokelib/core/programs.py
+++ b/buildscripts/resmokelib/core/programs.py
@@ -401,8 +401,36 @@ def mongo_shell_program(
     mongo_set_parameters = test_data.get("setParametersMongo", {}).copy()
 
     feature_flag_dict = {}
+    # In multiversion suites, exclude IFR (Incremental Feature Rollout) flags from
+    # TestData.setParameters. IFR flags are excluded from resmoke-managed multiversion
+    # fixtures by the Python fixture builders, but TestData.setParameters is consumed by
+    # JS test-created clusters (ShardingTest, ReplSetTest) which don't have the same
+    # filtering. Including IFR flags in multiversion suites causes them to leak into
+    # test-created clusters where they are incompatible — even latest-version nodes must
+    # not activate IFR-gated features when older nodes in the same cluster cannot handle
+    # the resulting commands. In non-multiversion suites all servers are latest-version,
+    # so IFR flags are safe to include.
+    #
+    # Multiversion can be signalled either via resmoke CLI flags (MIXED_BIN_VERSIONS,
+    # MULTIVERSION_BIN_VERSION) or via TestData variables set in suite YAML configs
+    # (useRandomBinVersionsWithinReplicaSet, mongosBinVersion). Both paths must be
+    # checked to catch suites like sharding_last_continuous where JS tests create
+    # their own mixed-version clusters using TestData.
+    is_multiversion = (
+        config.MIXED_BIN_VERSIONS is not None
+        or config.MULTIVERSION_BIN_VERSION is not None
+        or test_data.get("useRandomBinVersionsWithinReplicaSet") is not None
+        or test_data.get("mongosBinVersion") is not None
+    )
+    ifr_flags = set(config.IFR_FEATURE_FLAGS or [])
+
+    def include_flag(ff: str) -> bool:
+        if is_multiversion and ff in ifr_flags:
+            return False
+        return True
+
     if config.ENABLED_FEATURE_FLAGS is not None:
-        feature_flag_dict = {ff: "true" for ff in config.ENABLED_FEATURE_FLAGS}
+        feature_flag_dict = {ff: "true" for ff in config.ENABLED_FEATURE_FLAGS if include_flag(ff)}
 
     if config.DISABLED_FEATURE_FLAGS is not None:
         feature_flag_dict |= {ff: "false" for ff in config.DISABLED_FEATURE_FLAGS}
diff --git a/buildscripts/resmokelib/testing/fixtures/_builder.py b/buildscripts/resmokelib/testing/fixtures/_builder.py
index 1a0bb6d4a80..d0655baa64f 100644
--- a/buildscripts/resmokelib/testing/fixtures/_builder.py
+++ b/buildscripts/resmokelib/testing/fixtures/_builder.py
@@ -25,7 +25,9 @@ RETRIEVE_LOCK = threading.Lock()
 _BUILDERS = {}  # type: ignore
 
 
-def make_fixture(class_name, logger, job_num, *args, enable_feature_flags=True, **kwargs):
+def make_fixture(
+    class_name, logger, job_num, *args, enable_feature_flags=True, exclude_ifr_flags=False, **kwargs
+):
     """Provide factory function for creating Fixture instances."""
 
     fixturelib = FixtureLib()
@@ -46,6 +48,7 @@ def make_fixture(class_name, logger, job_num, *args, enable_feature_flags=True,
             fixturelib,
             *args,
             add_feature_flags=bool(config.ENABLED_FEATURE_FLAGS),
+            exclude_ifr_flags=exclude_ifr_flags,
             **kwargs,
         )
 
@@ -399,6 +402,7 @@ class ReplSetBuilder(FixtureBuilder):
             _class,
             mongod_logger,
             replset.job_num,
+            exclude_ifr_flags=is_multiversion,
             mongod_executable=executables[BinVersionEnum.NEW],
             mongod_options=new_fixture_mongod_options,
             preserve_dbpath=replset.preserve_dbpath,
@@ -750,6 +754,7 @@ class ShardedClusterBuilder(FixtureBuilder):
             _class,
             mongos_logger,
             sharded_cluster.job_num,
+            exclude_ifr_flags=is_multiversion,
             mongos_executable=executables[BinVersionEnum.NEW],
             **new_fixture_mongos_kwargs,
         )
diff --git a/buildscripts/resmokelib/testing/fixtures/fixturelib.py b/buildscripts/resmokelib/testing/fixtures/fixturelib.py
index ade7f66e412..1ddacc119c5 100644
--- a/buildscripts/resmokelib/testing/fixtures/fixturelib.py
+++ b/buildscripts/resmokelib/testing/fixtures/fixturelib.py
@@ -161,6 +161,7 @@ class _FixtureConfig(object):
         self.LAST_CONTINUOUS_MONGOS_BINARY = LAST_CONTINUOUS_MONGOS_BINARY
         self.USE_LEGACY_MULTIVERSION = config.USE_LEGACY_MULTIVERSION
         self.ENABLED_FEATURE_FLAGS = config.ENABLED_FEATURE_FLAGS
+        self.IFR_FEATURE_FLAGS = config.IFR_FEATURE_FLAGS
         self.EVERGREEN_TASK_ID = config.EVERGREEN_TASK_ID
         self.MAJORITY_READ_CONCERN = config.MAJORITY_READ_CONCERN
         self.NO_JOURNAL = config.NO_JOURNAL
diff --git a/buildscripts/resmokelib/testing/fixtures/shardedcluster.py b/buildscripts/resmokelib/testing/fixtures/shardedcluster.py
index e07a274fe7e..83cedb90cd4 100644
--- a/buildscripts/resmokelib/testing/fixtures/shardedcluster.py
+++ b/buildscripts/resmokelib/testing/fixtures/shardedcluster.py
@@ -957,6 +957,7 @@ class _MongoSFixture(interface.Fixture, interface._DockerComposeInterface):
         mongos_executable=None,
         mongos_options=None,
         add_feature_flags=False,
+        exclude_ifr_flags=False,
         use_priority_port=False,
         uds_path_prefix=None,
     ):
@@ -976,7 +977,10 @@ class _MongoSFixture(interface.Fixture, interface._DockerComposeInterface):
         ).copy()
 
         if add_feature_flags:
+            ifr_flags = set(self.config.IFR_FEATURE_FLAGS or [])
             for ff in self.config.ENABLED_FEATURE_FLAGS:
+                if exclude_ifr_flags and ff in ifr_flags:
+                    continue
                 self.mongos_options["set_parameters"][ff] = "true"
 
         self.mongos = None
diff --git a/buildscripts/resmokelib/testing/fixtures/standalone.py b/buildscripts/resmokelib/testing/fixtures/standalone.py
index 160707d8bec..f98769a42d7 100644
--- a/buildscripts/resmokelib/testing/fixtures/standalone.py
+++ b/buildscripts/resmokelib/testing/fixtures/standalone.py
@@ -36,6 +36,7 @@ class MongoDFixture(interface.Fixture, interface._DockerComposeInterface):
         mongod_executable: Optional[str] = None,
         mongod_options: Optional[dict] = None,
         add_feature_flags: bool = False,
+        exclude_ifr_flags: bool = False,
         dbpath_prefix: Optional[str] = None,
         preserve_dbpath: bool = False,
         port: Optional[int] = None,
@@ -54,6 +55,8 @@ class MongoDFixture(interface.Fixture, interface._DockerComposeInterface):
             mongod_executable (Optional[str], optional): Optional path to mongod executable. Defaults to None.
             mongod_options (Optional[dict], optional): Optional mongod startup options. Defaults to None.
             add_feature_flags (bool, optional): Sets all feature flags to true when set. Defaults to False.
+            exclude_ifr_flags (bool, optional): When True and add_feature_flags is True,
+                Incremental Feature Rollout (IFR) flags are excluded from injection (used in multiversion fixtures). Defaults to False.
             dbpath_prefix (Optional[str], optional): Sets the dbpath_prefix. Defaults to None.
             preserve_dbpath (bool, optional): preserve_dbpath. Defaults to False.
             port (Optional[int], optional): Port to use for mongod. Defaults to None.
@@ -103,7 +106,10 @@ class MongoDFixture(interface.Fixture, interface._DockerComposeInterface):
             self.mongod_options["set_parameters"] = {}
 
         if add_feature_flags:
+            ifr_flags = set(self.config.IFR_FEATURE_FLAGS or [])
             for ff in self.config.ENABLED_FEATURE_FLAGS:
+                if exclude_ifr_flags and ff in ifr_flags:
+                    continue
                 self.mongod_options["set_parameters"][ff] = "true"
 
         if "dbpath" in self.mongod_options and dbpath_prefix is not None:
diff --git a/buildscripts/tests/resmokelib/testing/fixtures/test_builder.py b/buildscripts/tests/resmokelib/testing/fixtures/test_builder.py
index 97546c55ed9..fe23bb1c686 100644
--- a/buildscripts/tests/resmokelib/testing/fixtures/test_builder.py
+++ b/buildscripts/tests/resmokelib/testing/fixtures/test_builder.py
@@ -160,3 +160,161 @@ class TestBuildShardedCluster(unittest.TestCase):
         self.assertNotIn(ff_name, sharded_cluster.shards[0].nodes[1].mongod_options[SET_PARAMS])
         self.assertNotIn(ff_name, sharded_cluster.shards[1].nodes[0].mongod_options[SET_PARAMS])
         self.assertNotIn(ff_name, sharded_cluster.mongos[0].mongos_options[SET_PARAMS])
+
+    def test_build_sharded_cluster_multiversion_excludes_ifr_flags(self):
+        """IFR flags should be excluded from new-binary nodes in multiversion mode.
+
+        Uses featureFlagTestIFR and featureFlagTestNonIFR defined in
+        buildscripts/resmokeconfig/feature_flag_test.idl. These are discovered
+        by the IDL scan in --runAllFeatureFlagTests.
+        """
+        ifr_flag = "featureFlagTestIFR"
+        non_ifr_flag = "featureFlagTestNonIFR"
+        parser.set_run_options("--runAllFeatureFlagTests", False)
+
+        self.assertIn(ifr_flag, config.IFR_FEATURE_FLAGS)
+        self.assertNotIn(non_ifr_flag, config.IFR_FEATURE_FLAGS)
+        self.assertIn(ifr_flag, config.ENABLED_FEATURE_FLAGS)
+        self.assertIn(non_ifr_flag, config.ENABLED_FEATURE_FLAGS)
+
+        fixture_config = {
+            "mongod_options": {SET_PARAMS: {"enableTestCommands": 1}},
+            "configsvr_options": {"num_nodes": 2},
+            "num_shards": 1,
+            "num_rs_nodes_per_shard": 2,
+            "mixed_bin_versions": "new_old",
+            "old_bin_version": "last_lts",
+        }
+        sharded_cluster = under_test.make_fixture(
+            self.fixture_class_name, self.mock_logger, self.job_num, **fixture_config
+        )
+
+        # Non-IFR flag IS set on new-binary configsvr nodes
+        self.assertIn(
+            non_ifr_flag,
+            sharded_cluster.configsvr.nodes[0].mongod_options[SET_PARAMS],
+        )
+        self.assertIn(
+            non_ifr_flag,
+            sharded_cluster.configsvr.nodes[1].mongod_options[SET_PARAMS],
+        )
+        # IFR flag is NOT set on new-binary configsvr nodes (multiversion)
+        self.assertNotIn(
+            ifr_flag,
+            sharded_cluster.configsvr.nodes[0].mongod_options[SET_PARAMS],
+        )
+        self.assertNotIn(
+            ifr_flag,
+            sharded_cluster.configsvr.nodes[1].mongod_options[SET_PARAMS],
+        )
+
+        # Non-IFR flag IS set on new-binary shard node
+        self.assertIn(
+            non_ifr_flag,
+            sharded_cluster.shards[0].nodes[0].mongod_options[SET_PARAMS],
+        )
+        # IFR flag is NOT set on new-binary shard node (multiversion)
+        self.assertNotIn(
+            ifr_flag,
+            sharded_cluster.shards[0].nodes[0].mongod_options[SET_PARAMS],
+        )
+        # Neither flag is on old-binary shard node
+        self.assertNotIn(
+            ifr_flag,
+            sharded_cluster.shards[0].nodes[1].mongod_options[SET_PARAMS],
+        )
+        self.assertNotIn(
+            non_ifr_flag,
+            sharded_cluster.shards[0].nodes[1].mongod_options[SET_PARAMS],
+        )
+
+        # Access the new mongos fixture inside the FixtureContainer (which starts
+        # with the old version in multiversion mode).
+        new_mongos = sharded_cluster.mongos[0]._fixtures[under_test.BinVersionEnum.NEW]
+        # IFR flag is NOT set on new-binary mongos (multiversion)
+        self.assertNotIn(ifr_flag, new_mongos.mongos_options[SET_PARAMS])
+        # Non-IFR flag IS set on new-binary mongos
+        self.assertIn(non_ifr_flag, new_mongos.mongos_options[SET_PARAMS])
+
+    def test_build_sharded_cluster_non_multiversion_keeps_ifr_flags(self):
+        """IFR flags should be included in non-multiversion mode."""
+        ifr_flag = "featureFlagTestIFR"
+        parser.set_run_options("--runAllFeatureFlagTests", False)
+
+        fixture_config = {"mongod_options": {SET_PARAMS: {"enableTestCommands": 1}}}
+        sharded_cluster = under_test.make_fixture(
+            self.fixture_class_name, self.mock_logger, self.job_num, **fixture_config
+        )
+
+        # IFR flag IS set when not in multiversion mode
+        self.assertIn(
+            ifr_flag,
+            sharded_cluster.configsvr.nodes[0].mongod_options[SET_PARAMS],
+        )
+        self.assertIn(
+            ifr_flag,
+            sharded_cluster.shards[0].nodes[0].mongod_options[SET_PARAMS],
+        )
+        self.assertIn(
+            ifr_flag,
+            sharded_cluster.mongos[0].mongos_options[SET_PARAMS],
+        )
+
+
+class TestMakeFixtureIFRExclusion(unittest.TestCase):
+    """Test that make_fixture correctly handles exclude_ifr_flags for MongoDFixture.
+
+    Uses featureFlagTestIFR and featureFlagTestNonIFR defined in
+    buildscripts/resmokeconfig/feature_flag_test.idl.
+    """
+
+    mock_logger = None
+    job_num = 0
+
+    @classmethod
+    def setUpClass(cls):
+        cls.mock_logger = MagicMock(spec=logging.Logger)
+        logging.loggers._FIXTURE_LOGGER_REGISTRY[cls.job_num] = cls.mock_logger
+
+    def tearDown(self):
+        network.PortAllocator.reset()
+
+    def test_mongod_exclude_ifr_flags(self):
+        """MongoDFixture should exclude IFR flags when exclude_ifr_flags=True."""
+        ifr_flag = "featureFlagTestIFR"
+        non_ifr_flag = "featureFlagTestNonIFR"
+        parser.set_run_options("--runAllFeatureFlagTests", False)
+
+        mongod = under_test.make_fixture(
+            "MongoDFixture",
+            self.mock_logger,
+            self.job_num,
+            exclude_ifr_flags=True,
+        )
+        self.assertNotIn(ifr_flag, mongod.mongod_options[SET_PARAMS])
+        self.assertIn(non_ifr_flag, mongod.mongod_options[SET_PARAMS])
+
+    def test_mongod_include_ifr_flags_when_not_excluded(self):
+        """MongoDFixture should include IFR flags when exclude_ifr_flags=False (default)."""
+        ifr_flag = "featureFlagTestIFR"
+        parser.set_run_options("--runAllFeatureFlagTests", False)
+
+        mongod = under_test.make_fixture(
+            "MongoDFixture",
+            self.mock_logger,
+            self.job_num,
+        )
+        self.assertIn(ifr_flag, mongod.mongod_options[SET_PARAMS])
+
+    def test_mongod_no_flags_when_feature_flags_disabled(self):
+        """MongoDFixture should not inject any flags when enable_feature_flags=False."""
+        ifr_flag = "featureFlagTestIFR"
+        parser.set_run_options("--runAllFeatureFlagTests", False)
+
+        mongod = under_test.make_fixture(
+            "MongoDFixture",
+            self.mock_logger,
+            self.job_num,
+            enable_feature_flags=False,
+        )
+        self.assertNotIn(ifr_flag, mongod.mongod_options[SET_PARAMS])
diff --git a/src/mongo/db/feature_flag_test.idl.tpl b/src/mongo/db/feature_flag_test.idl.tpl
index afecbb238ac..acfe636db1f 100644
--- a/src/mongo/db/feature_flag_test.idl.tpl
+++ b/src/mongo/db/feature_flag_test.idl.tpl
@@ -103,6 +103,18 @@ feature_flags:
       serialize_on_outgoing_requests: true
       version: $ver_str(latest)
 
+    featureFlagTestIFR:
+      description: "IFR feature flag used by fixture builder unit tests"
+      cpp_varname: gFeatureFlagTestIFR
+      incremental_rollout_phase: in_development
+      fcv_gated: false
+
+    featureFlagTestNonIFR:
+      description: "Non-IFR feature flag used by fixture builder unit tests"
+      cpp_varname: gFeatureFlagTestNonIFR
+      default: false
+      fcv_gated: false
+
 server_parameters:
     spTestNeedsFeatureFlagToaster:
       description: "Server Parameter gated on featureFlagToaster"