diff --git a/libc/cmake/modules/LLVMLibCTestRules.cmake b/libc/cmake/modules/LLVMLibCTestRules.cmake
index fc66c129609456..f7ca6a2e702114 100644
--- a/libc/cmake/modules/LLVMLibCTestRules.cmake
+++ b/libc/cmake/modules/LLVMLibCTestRules.cmake
@@ -636,6 +636,12 @@ function(add_libc_hermetic_test test_name)
       libc.src.string.memset
       libc.src.__support.StringUtil.error_to_string
   )
+
+  if(TARGET libc.src.time.clock)
+    # We will link in the 'clock' implementation if it exists for test timing.
+    list(APPEND fq_deps_list libc.src.time.clock)
+  endif()
+
   list(REMOVE_DUPLICATES fq_deps_list)
 
   # TODO: Instead of gathering internal object files from entrypoints,
diff --git a/libc/test/UnitTest/CMakeLists.txt b/libc/test/UnitTest/CMakeLists.txt
index 4d384535581267..9baa41874a83db 100644
--- a/libc/test/UnitTest/CMakeLists.txt
+++ b/libc/test/UnitTest/CMakeLists.txt
@@ -28,6 +28,9 @@ function(add_unittest_framework_library name)
     )
     target_include_directories(${lib} PUBLIC ${LIBC_SOURCE_DIR})
     target_compile_options(${lib} PRIVATE -fno-exceptions -fno-rtti)
+    if(TARGET libc.src.time.clock)
+      target_compile_definitions(${lib} PRIVATE TARGET_SUPPORTS_CLOCK)
+    endif()
   endforeach()
   target_include_directories(${name}.hermetic PRIVATE ${LIBC_BUILD_DIR}/include)
   target_compile_options(${name}.hermetic
diff --git a/libc/test/UnitTest/LibcTest.cpp b/libc/test/UnitTest/LibcTest.cpp
index 5c27e2e69bead9..201b40a178dca0 100644
--- a/libc/test/UnitTest/LibcTest.cpp
+++ b/libc/test/UnitTest/LibcTest.cpp
@@ -15,20 +15,13 @@
 
 #if __STDC_HOSTED__
 #include <time.h>
-#elif defined(LIBC_TARGET_ARCH_IS_GPU)
-#include "src/__support/GPU/utils.h"
-static long clock() { return LIBC_NAMESPACE::gpu::fixed_frequency_clock(); }
-#if defined(LIBC_TARGET_ARCH_IS_NVPTX)
-#define CLOCKS_PER_SEC 1000000000UL
-#else
-// The AMDGPU loader needs to initialize this at runtime by querying the driver.
-extern "C" [[gnu::visibility("protected")]] uint64_t
-    [[clang::address_space(4)]] __llvm_libc_clock_freq;
-#define CLOCKS_PER_SEC __llvm_libc_clock_freq
-#endif
-#else
-static long clock() { return 0; }
-#define CLOCKS_PER_SEC 1
+#define LIBC_TEST_USE_CLOCK
+#elif defined(TARGET_SUPPORTS_CLOCK)
+#include <time.h>
+
+#include "src/time/clock.h"
+extern "C" clock_t clock() noexcept { return LIBC_NAMESPACE::clock(); }
+#define LIBC_TEST_USE_CLOCK
 #endif
 
 namespace LIBC_NAMESPACE {
@@ -147,7 +140,7 @@ int Test::runTests(const char *TestFilter) {
       break;
     case RunContext::RunResult::Pass:
       tlog << GREEN << "[       OK ] " << RESET << TestName;
-#if __STDC_HOSTED__ || defined(LIBC_TARGET_ARCH_IS_GPU)
+#ifdef LIBC_TEST_USE_CLOCK
       tlog << " (took ";
       if (start_time > end_time) {
         tlog << "unknown - try rerunning)\n";