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
@@ -693,10 +693,17 @@
 
 # A convenience function to add both a unit test as well as a hermetic test.
 function(add_libc_test test_name)
-  if(LIBC_ENABLE_UNITTESTS)
-    add_libc_unittest(${test_name}.__unit__ ${ARGN})
+  cmake_parse_arguments(
+    "LIBC_TEST"
+    "UNIT_TEST_ONLY;HERMETIC_TEST_ONLY" # Optional arguments
+    "" # Single value arguments
+    "" # Multi-value arguments
+    ${ARGN}
+  )
+  if(LIBC_ENABLE_UNITTESTS AND NOT LIBC_TEST_HERMETIC_TEST_ONLY)
+    add_libc_unittest(${test_name}.__unit__ ${LIBC_TEST_UNPARSED_ARGUMENTS})
   endif()
-  if(LIBC_ENABLE_HERMETIC_TESTS)
-    add_libc_hermetic_test(${test_name}.__hermetic__ ${ARGN})
+  if(LIBC_ENABLE_HERMETIC_TESTS AND NOT LIBC_TEST_UNIT_TEST_ONLY)
+    add_libc_hermetic_test(${test_name}.__hermetic__ ${LIBC_TEST_UNPARSED_ARGUMENTS})
   endif()
 endfunction(add_libc_test)
diff --git a/libc/test/src/string/memory_utils/CMakeLists.txt b/libc/test/src/string/memory_utils/CMakeLists.txt
--- a/libc/test/src/string/memory_utils/CMakeLists.txt
+++ b/libc/test/src/string/memory_utils/CMakeLists.txt
@@ -1,5 +1,5 @@
-# This test uses too much memory to be made hermetic.
-add_libc_unittest(
+# This test currently uses too much memory to be made hermetic.
+add_libc_test(
   utils_test
   SUITE
     libc-string-tests
@@ -15,4 +15,5 @@
     libc.src.__support.CPP.span
     libc.src.__support.macros.sanitizer
     libc.src.string.memory_utils.memory_utils
+  UNIT_TEST_ONLY
 )