diff --git a/libc/cmake/modules/LLVMLibCTestRules.cmake b/libc/cmake/modules/LLVMLibCTestRules.cmake
--- a/libc/cmake/modules/LLVMLibCTestRules.cmake
+++ b/libc/cmake/modules/LLVMLibCTestRules.cmake
@@ -705,10 +705,18 @@
     "" # Multi-value arguments
     ${ARGN}
   )
+  get_fq_target_name(${test_name} fq_target_name)
+  if(LIBC_TEST_UNIT_TEST_ONLY AND LIBC_TEST_HERMETIC_TEST_ONLY)
+    message(FATAL_ERROR
+            "${fq_target_name}: Only one of UNIT_TEST_ONLY and HERMETIC_TEST_ONLY can be listed.")
+  endif()
+  add_custom_target(${fq_target_name})
   if(LIBC_ENABLE_UNITTESTS AND NOT LIBC_TEST_HERMETIC_TEST_ONLY)
     add_libc_unittest(${test_name}.__unit__ ${LIBC_TEST_UNPARSED_ARGUMENTS})
+    add_dependencies(${fq_target_name} ${fq_target_name}.__unit__)
   endif()
   if(LIBC_ENABLE_HERMETIC_TESTS AND NOT LIBC_TEST_UNIT_TEST_ONLY)
     add_libc_hermetic_test(${test_name}.__hermetic__ ${LIBC_TEST_UNPARSED_ARGUMENTS})
+    add_dependencies(${fq_target_name} ${fq_target_name}.__hermetic__)
   endif()
 endfunction(add_libc_test)