diff --git a/examples/models/llama/export_llama_lib.py b/examples/models/llama/export_llama_lib.py
index c22bdac4ed2..5cdc9a40940 100644
--- a/examples/models/llama/export_llama_lib.py
+++ b/examples/models/llama/export_llama_lib.py
@@ -1805,9 +1805,7 @@ def _export_llama(llm_config: LlmConfig) -> LLMEdgeManager:  # noqa: C901
             verbose=llm_config.debug.verbose,
         )
     elif llm_config.backend.coreml.enabled and not (
-        llm_config.backend.vulkan.enabled
-        or llm_config.backend.mps.enabled
-        or llm_config.backend.qnn.enabled
+        llm_config.backend.vulkan.enabled or llm_config.backend.qnn.enabled
     ):
         builder = _to_edge_and_lower_llama_coreml(
             builder_exported,
diff --git a/examples/models/llama/tests/test_export_llama_lib.py b/examples/models/llama/tests/test_export_llama_lib.py
index 40ba701f84e..a803a59db52 100644
--- a/examples/models/llama/tests/test_export_llama_lib.py
+++ b/examples/models/llama/tests/test_export_llama_lib.py
@@ -6,6 +6,7 @@
 # LICENSE file in the root directory of this source tree.
 
 import unittest
+from unittest.mock import patch
 
 from executorch.devtools.backend_debug import get_delegation_info
 
@@ -23,6 +24,7 @@
     TOSAQuantizer = None
     VgfQuantizer = None
 
+from executorch.examples.models.llama import export_llama_lib
 from executorch.examples.models.llama.export_llama_lib import (
     _export_llama,
     build_args_parser,
@@ -41,6 +43,52 @@
 
 
 class ExportLlamaLibTest(unittest.TestCase):
+    def _assert_routes_to(self, lowering, coreml=False, vulkan=False, qnn=False):
+        """Assert which lowering an export routes to, without running one."""
+        llm_config = LlmConfig()
+        llm_config.backend.coreml.enabled = coreml
+        llm_config.backend.vulkan.enabled = vulkan
+        llm_config.backend.qnn.enabled = qnn
+        # _validate_args rejects dynamic shapes when Core ML or QNN is enabled.
+        llm_config.model.enable_dynamic_shape = False
+
+        class Reached(Exception):
+            pass
+
+        with patch.object(export_llama_lib, lowering, side_effect=Reached) as target:
+            with self.assertRaises(Reached):
+                _export_llama(llm_config)
+        target.assert_called_once()
+        return target
+
+    def test_core_ml_alone_routes_to_the_core_ml_lowering(self):
+        """Core ML on its own must reach the Core ML lowering.
+
+        The guard read a backend config field that no longer exists, so this raised AttributeError
+        before reaching any lowering.
+        """
+        self._assert_routes_to("_to_edge_and_lower_llama_coreml", coreml=True)
+
+    def test_core_ml_with_qnn_routes_to_the_combined_lowering(self):
+        """Core ML with QNN must keep the QNN partitioner, so it takes the combined lowering."""
+        target = self._assert_routes_to(
+            "_to_edge_and_lower_llama", coreml=True, qnn=True
+        )
+        self.assertTrue(target.call_args.kwargs["coreml"])
+        self.assertTrue(target.call_args.kwargs["qnn"])
+
+    def test_core_ml_with_vulkan_routes_to_the_combined_lowering(self):
+        """Core ML with Vulkan must keep the Vulkan partitioner the same way.
+
+        This is what pins the Vulkan half of the exclusion clause: the Core ML lowering takes no
+        Vulkan argument, so routing there would drop the partitioner silently.
+        """
+        target = self._assert_routes_to(
+            "_to_edge_and_lower_llama", coreml=True, vulkan=True
+        )
+        self.assertTrue(target.call_args.kwargs["coreml"])
+        self.assertTrue(target.call_args.kwargs["vulkan"])
+
     def test_has_expected_ops_and_op_counts(self):
         """
         Checks the presence of unwanted expensive ops.