diff --git a/libc/cmake/modules/LLVMLibCObjectRules.cmake b/libc/cmake/modules/LLVMLibCObjectRules.cmake
--- a/libc/cmake/modules/LLVMLibCObjectRules.cmake
+++ b/libc/cmake/modules/LLVMLibCObjectRules.cmake
@@ -3,7 +3,7 @@
 function(_get_common_compile_options output_var)
   set(compile_options ${LIBC_COMPILE_OPTIONS_DEFAULT} ${ARGN})
   if(NOT ${LIBC_TARGET_OS} STREQUAL "windows")
-    set(compile_options ${compile_options} -fpie -ffreestanding)
+    set(compile_options ${compile_options} -fpie -ffreestanding -fno-builtin)
   endif()
   if(LLVM_COMPILER_IS_GCC_COMPATIBLE)
     list(APPEND compile_options "-fno-exceptions")
diff --git a/libc/src/string/CMakeLists.txt b/libc/src/string/CMakeLists.txt
--- a/libc/src/string/CMakeLists.txt
+++ b/libc/src/string/CMakeLists.txt
@@ -279,7 +279,6 @@
     ${ARGN})
 
   if("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang")
-    list(APPEND ADD_IMPL_MLLVM_COMPILE_OPTIONS "-combiner-global-alias-analysis")
     # Note that '-mllvm' needs to be prefixed with 'SHELL:' to prevent CMake flag deduplication.
     foreach(opt IN LISTS ADD_IMPL_MLLVM_COMPILE_OPTIONS)
       list(APPEND ADD_IMPL_COMPILE_OPTIONS "SHELL:-mllvm ${opt}")
@@ -309,9 +308,6 @@
     DEPENDS
       .memory_utils.memory_utils
       libc.include.string
-    COMPILE_OPTIONS
-      -fno-builtin-memcmp
-      -fno-builtin-bcmp
     ${ARGN}
   )
 endfunction()
@@ -339,8 +335,6 @@
     DEPENDS
       .memory_utils.memset_implementation
       libc.include.string
-    COMPILE_OPTIONS
-      -fno-builtin-bzero
     ${ARGN}
   )
 endfunction()
@@ -368,8 +362,6 @@
     DEPENDS
       .memory_utils.memcmp_implementation
       libc.include.string
-    COMPILE_OPTIONS
-      -fno-builtin-memcmp
     ${ARGN}
   )
 endfunction()
@@ -400,8 +392,6 @@
     DEPENDS
       .memory_utils.memcpy_implementation
       libc.include.string
-    COMPILE_OPTIONS
-      -fno-builtin-memcpy
     ${ARGN}
   )
 endfunction()
@@ -434,8 +424,6 @@
     DEPENDS
       .memory_utils.memory_utils
       libc.include.string
-    COMPILE_OPTIONS
-      -fno-builtin
     ${ARGN}
   )
 endfunction()
@@ -468,8 +456,6 @@
     DEPENDS
       .memory_utils.memset_implementation
       libc.include.string
-    COMPILE_OPTIONS
-      -fno-builtin-memset
     ${ARGN}
   )
 endfunction()
diff --git a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
--- a/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
+++ b/utils/bazel/llvm-project-overlay/libc/BUILD.bazel
@@ -9,6 +9,7 @@
 
 package(
     default_visibility = ["//visibility:public"],
+    features = ["-header_modules"],
     licenses = ["notice"],
 )
 
@@ -85,7 +86,10 @@
     hdrs = [
         "src/__support/CPP/UInt.h",
     ],
-    deps = [":libc_root","__support_cpp_array"],
+    deps = [
+        "__support_cpp_array",
+        ":libc_root",
+    ],
 )
 
 cc_library(
@@ -93,7 +97,10 @@
     hdrs = [
         "src/__support/CPP/TypeTraits.h",
     ],
-    deps = [":libc_root","__support_cpp_uint"],
+    deps = [
+        "__support_cpp_uint",
+        ":libc_root",
+    ],
 )
 
 cc_library(
@@ -806,12 +813,6 @@
     name = "memcpy",
     srcs = ["src/string/memcpy.cpp"],
     hdrs = ["src/string/memcpy.h"],
-    copts = [
-        "-fno-builtin-memcpy",
-        "-fno-builtin-memmove",
-        "-mllvm -combiner-global-alias-analysis",
-        "-mllvm --tail-merge-threshold=0",
-    ],
     features = no_sanitize_features,
     deps = [
         ":__support_common",
@@ -823,10 +824,6 @@
     name = "memset",
     srcs = ["src/string/memset.cpp"],
     hdrs = ["src/string/memset.h"],
-    copts = [
-        "-fno-builtin-memset",
-        "-mllvm -combiner-global-alias-analysis",
-    ],
     features = no_sanitize_features,
     deps = [
         ":__support_common",
@@ -838,10 +835,6 @@
     name = "memmove",
     srcs = ["src/string/memmove.cpp"],
     hdrs = ["src/string/memmove.h"],
-    copts = [
-        "-fno-builtin-memmove",
-        "-mllvm -combiner-global-alias-analysis",
-    ],
     features = no_sanitize_features,
     deps = [
         ":__support_common",
@@ -855,10 +848,6 @@
     name = "memcmp",
     srcs = ["src/string/memcmp.cpp"],
     hdrs = ["src/string/memcmp.h"],
-    copts = [
-        "-fno-builtin-memcmp",
-        "-mllvm -combiner-global-alias-analysis",
-    ],
     features = no_sanitize_features,
     deps = [
         ":__support_common",
@@ -871,10 +860,6 @@
     name = "bcmp",
     srcs = ["src/string/bcmp.cpp"],
     hdrs = ["src/string/bcmp.h"],
-    copts = [
-        "-fno-builtin-bcmp",
-        "-fno-builtin-memcmp",
-    ],
     features = no_sanitize_features,
     deps = [
         ":__support_common",
@@ -886,11 +871,6 @@
     name = "bzero",
     srcs = ["src/string/bzero.cpp"],
     hdrs = ["src/string/bzero.h"],
-    copts = [
-        "-fno-builtin-bzero",
-        "-fno-builtin-memset",
-        "-mllvm -combiner-global-alias-analysis",
-    ],
     features = no_sanitize_features,
     deps = [
         ":__support_common",
diff --git a/utils/bazel/llvm-project-overlay/libc/libc_build_rules.bzl b/utils/bazel/llvm-project-overlay/libc/libc_build_rules.bzl
--- a/utils/bazel/llvm-project-overlay/libc/libc_build_rules.bzl
+++ b/utils/bazel/llvm-project-overlay/libc/libc_build_rules.bzl
@@ -31,6 +31,7 @@
     deps.append(LIBC_ROOT_TARGET)
     copts = copts or []
     copts.append("-O3")
+    copts.append("-fno-builtin")
 
     # We compile the code twice, the first target is suffixed with ".__internal__" and contains the
     # C++ functions in the "__llvm_libc" namespace. This allows us to test the function in the