From 267b0ea6e87a25044da047486d3877ebc1b5029b Mon Sep 17 00:00:00 2001
From: Ilya Tokar <tokarip@google.com>
Date: Wed, 25 Mar 2026 15:14:27 -0400
Subject: [PATCH] [libc][x86] add MEMCPY_X86_USE_NTA_STORES to config (#188321)

Add LIBC_CONF_COPT_MEMCPY_X86_USE_NTA_STORES to cmake/bazel/json config.
---
 libc/cmake/modules/LLVMLibCCompileOptionRules.cmake           | 4 ++++
 libc/config/config.json                                       | 4 ++++
 .../llvm-project-overlay/libc/libc_configure_options.bzl      | 1 +
 3 files changed, 9 insertions(+)

diff --git a/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake b/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
index 1ce027114f73..2e2c5e3ad747 100644
--- a/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
+++ b/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
@@ -100,6 +100,10 @@ function(_get_compile_options_from_config output_var)
     list(APPEND config_options "-DLIBC_COPT_MEMSET_X86_USE_SOFTWARE_PREFETCHING")
   endif()
 
+  if(LIBC_CONF_COPT_MEMCPY_X86_USE_NTA_STORES)
+    list(APPEND config_options "-DLIBC_COPT_MEMCPY_X86_USE_NTA_STORES")
+  endif()
+
   if(LIBC_TYPES_TIME_T_IS_32_BIT AND LLVM_LIBC_FULL_BUILD)
     list(APPEND config_options "-DLIBC_TYPES_TIME_T_IS_32_BIT")
   endif()
diff --git a/libc/config/config.json b/libc/config/config.json
index 2ab09f6717f2..39cb2d8cfa33 100644
--- a/libc/config/config.json
+++ b/libc/config/config.json
@@ -101,6 +101,10 @@
     "LIBC_CONF_MEMSET_X86_USE_SOFTWARE_PREFETCHING": {
       "value": false,
       "doc": "Inserts prefetch for write instructions (PREFETCHW) for memset on x86 to recover performance when hardware prefetcher is disabled."
+    },
+    "LIBC_CONF_COPT_MEMCPY_X86_USE_NTA_STORES": {
+      "value": false,
+      "doc": "Use Non-temporal stores in memcpy on x86 to improve performance of large copies."
     }
   },
   "ctype": {
diff --git a/utils/bazel/llvm-project-overlay/libc/libc_configure_options.bzl b/utils/bazel/llvm-project-overlay/libc/libc_configure_options.bzl
index 1c2b65ea2011..340893850bfe 100644
--- a/utils/bazel/llvm-project-overlay/libc/libc_configure_options.bzl
+++ b/utils/bazel/llvm-project-overlay/libc/libc_configure_options.bzl
@@ -24,6 +24,7 @@ LIBC_CONFIGURE_OPTIONS = [
     # Documentation in libc/src/string/memory_utils/...
     # "LIBC_COPT_MEMCPY_USE_EMBEDDED_TINY",
     # "LIBC_COPT_MEMCPY_X86_USE_REPMOVSB_FROM_SIZE",
+    # "LIBC_COPT_MEMCPY_X86_USE_NTA_STORES",
     "LIBC_COPT_MEMCPY_X86_USE_SOFTWARE_PREFETCHING",
     "LIBC_COPT_MEMSET_X86_USE_SOFTWARE_PREFETCHING",