diff --git a/libc/cmake/modules/LLVMLibCCheckCpuFeatures.cmake b/libc/cmake/modules/LLVMLibCCheckCpuFeatures.cmake
new file mode 100644
--- /dev/null
+++ b/libc/cmake/modules/LLVMLibCCheckCpuFeatures.cmake
@@ -0,0 +1,53 @@
+set(ALL_CPU_FEATURES)
+
+# Defines a cpu feature
+# - Adds the feature to ALL_CPU_FEATURES
+# - Defines enabling and disabling flags for the feature
+#   CPU_FEATURES_<FEATURE>_ENABLE_FLAG
+#   CPU_FEATURES_<FEATURE>_DISABLE_FLAG
+function(define_cpu_feature_optimization name)
+  cmake_parse_arguments(
+    "DCFO"
+    "" # No optional arguments
+    "CLANG_FLAG" # Single value arguments
+    ""     # Multi value arguments
+    ${ARGN}
+  )
+  list(APPEND ALL_CPU_FEATURES ${name})
+  set(ALL_CPU_FEATURES ${ALL_CPU_FEATURES} PARENT_SCOPE)
+  set(CPU_FEATURES_${name}_ENABLE_FLAG "-m${DCFO_CLANG_FLAG}" PARENT_SCOPE)
+  set(CPU_FEATURES_${name}_DISABLE_FLAG "-mno-${DCFO_CLANG_FLAG}" PARENT_SCOPE)
+endfunction()
+
+if(${LIBC_TARGET_MACHINE} MATCHES "x86|x86_64")
+    define_cpu_feature_optimization(SSE CLANG_FLAG sse)
+    define_cpu_feature_optimization(SSE2 CLANG_FLAG sse2)
+    define_cpu_feature_optimization(AVX CLANG_FLAG avx)
+    define_cpu_feature_optimization(AVX512F CLANG_FLAG avx512f)
+endif()
+
+set(HOST_CPU_FEATURES)
+function(check_cpu_features feature)
+    if(NOT ${feature} IN_LIST ALL_CPU_FEATURES)
+        message(FATAL_ERROR "${feature} is not part of available ${ALL_CPU_FEATURES}")
+    endif()
+    string(TOLOWER ${feature} lowercase_feature)
+    try_run(
+        run_result
+        compile_result
+        "${CMAKE_CURRENT_BINARY_DIR}/check_${lowercase_feature}"
+        "${CMAKE_MODULE_PATH}/cpu_features/check_${lowercase_feature}.cpp"
+        COMPILE_DEFINITIONS ${CPU_FEATURES_${feature}_ENABLE_FLAG}
+        OUTPUT_VARIABLE compile_output
+    )
+    if(${compile_result} AND ("${run_result}" EQUAL 0))
+        list(APPEND HOST_CPU_FEATURES ${feature})
+        set(HOST_CPU_FEATURES ${HOST_CPU_FEATURES} PARENT_SCOPE)
+    endif()
+endfunction()
+
+# Tests the host system against all cpu features and populates
+# HOST_CPU_FEATURES with a subset of ALL_CPU_FEATURES.
+foreach(feature IN LISTS ALL_CPU_FEATURES)
+    check_cpu_features(${feature})
+endforeach(feature)
diff --git a/libc/cmake/modules/cpu_features/check_avx.cpp b/libc/cmake/modules/cpu_features/check_avx.cpp
new file mode 100644
--- /dev/null
+++ b/libc/cmake/modules/cpu_features/check_avx.cpp
@@ -0,0 +1,8 @@
+#if !defined __AVX__
+#error "missing __AVX__"
+#endif
+#include <immintrin.h>
+int main() {
+  (void)_mm256_set1_epi8('0');
+  return 0;
+}
diff --git a/libc/cmake/modules/cpu_features/check_avx512f.cpp b/libc/cmake/modules/cpu_features/check_avx512f.cpp
new file mode 100644
--- /dev/null
+++ b/libc/cmake/modules/cpu_features/check_avx512f.cpp
@@ -0,0 +1,8 @@
+#if !defined __AVX512F__
+#error "missing __AVX512F__"
+#endif
+#include <immintrin.h>
+int main() {
+  (void)_mm512_undefined();
+  return 0;
+}
diff --git a/libc/cmake/modules/cpu_features/check_sse.cpp b/libc/cmake/modules/cpu_features/check_sse.cpp
new file mode 100644
--- /dev/null
+++ b/libc/cmake/modules/cpu_features/check_sse.cpp
@@ -0,0 +1,8 @@
+#if !defined __SSE__
+#error "missing __SSE__"
+#endif
+#include <immintrin.h>
+int main() {
+  (void)_mm_set_ss(1.0f);
+  return 0;
+}
diff --git a/libc/cmake/modules/cpu_features/check_sse2.cpp b/libc/cmake/modules/cpu_features/check_sse2.cpp
new file mode 100644
--- /dev/null
+++ b/libc/cmake/modules/cpu_features/check_sse2.cpp
@@ -0,0 +1,8 @@
+#if !defined __SSE2__
+#error "missing __SSE2__"
+#endif
+#include <immintrin.h>
+int main() {
+  (void)_mm_set1_epi8('0');
+  return 0;
+}