diff --git a/libc/src/__support/CMakeLists.txt b/libc/src/__support/CMakeLists.txt
--- a/libc/src/__support/CMakeLists.txt
+++ b/libc/src/__support/CMakeLists.txt
@@ -64,7 +64,6 @@
   DEPENDS
     .ctype_utils
     .str_to_num_result
-    libc.include.errno
     libc.src.errno.errno
     libc.src.__support.CPP.limits
     libc.src.__support.common
diff --git a/libc/src/__support/File/CMakeLists.txt b/libc/src/__support/File/CMakeLists.txt
--- a/libc/src/__support/File/CMakeLists.txt
+++ b/libc/src/__support/File/CMakeLists.txt
@@ -11,7 +11,7 @@
   HDRS
     file.h
   DEPENDS
-    libc.include.errno
+    
     libc.src.__support.CPP.new
     libc.src.__support.CPP.span
     libc.src.__support.threads.mutex
@@ -37,7 +37,7 @@
       ${LIBC_TARGET_OS}_file.cpp
     DEPENDS
       .file
-      libc.include.errno
+      
       libc.include.fcntl
       libc.include.stdio
       libc.include.sys_syscall
@@ -55,7 +55,6 @@
       ${LIBC_TARGET_OS}_dir.cpp
     DEPENDS
       .dir
-      libc.include.errno
       libc.include.fcntl
       libc.include.sys_syscall
       libc.src.__support.OSUtil.osutil
diff --git a/libc/src/__support/File/dir.cpp b/libc/src/__support/File/dir.cpp
--- a/libc/src/__support/File/dir.cpp
+++ b/libc/src/__support/File/dir.cpp
@@ -10,8 +10,8 @@
 
 #include "src/__support/CPP/new.h"
 #include "src/__support/error_or.h"
+#include "src/errno/libc_errno.h" // For error macros
 
-#include <errno.h>
 #include <stdlib.h>
 
 namespace __llvm_libc {
diff --git a/libc/src/__support/File/file.cpp b/libc/src/__support/File/file.cpp
--- a/libc/src/__support/File/file.cpp
+++ b/libc/src/__support/File/file.cpp
@@ -10,8 +10,8 @@
 
 #include "src/__support/CPP/new.h"
 #include "src/__support/CPP/span.h"
+#include "src/errno/libc_errno.h" // For error macros
 
-#include <errno.h> // For error macros
 #include <stdio.h>
 #include <stdlib.h>
 
diff --git a/libc/src/__support/File/linux_file.cpp b/libc/src/__support/File/linux_file.cpp
--- a/libc/src/__support/File/linux_file.cpp
+++ b/libc/src/__support/File/linux_file.cpp
@@ -10,8 +10,8 @@
 
 #include "src/__support/CPP/new.h"
 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/errno/libc_errno.h"         // For error macros
 
-#include <errno.h> // For error macros
 #include <fcntl.h> // For mode_t and other flags to the open syscall
 #include <stdio.h>
 #include <sys/syscall.h> // For syscall numbers
diff --git a/libc/src/__support/StringUtil/CMakeLists.txt b/libc/src/__support/StringUtil/CMakeLists.txt
--- a/libc/src/__support/StringUtil/CMakeLists.txt
+++ b/libc/src/__support/StringUtil/CMakeLists.txt
@@ -15,7 +15,6 @@
     error_to_string.cpp
   DEPENDS
   .message_mapper
-  libc.include.errno
   libc.src.__support.CPP.span
   libc.src.__support.CPP.string_view
   libc.src.__support.CPP.stringstream
diff --git a/libc/src/__support/StringUtil/error_to_string.cpp b/libc/src/__support/StringUtil/error_to_string.cpp
--- a/libc/src/__support/StringUtil/error_to_string.cpp
+++ b/libc/src/__support/StringUtil/error_to_string.cpp
@@ -13,8 +13,8 @@
 #include "src/__support/CPP/stringstream.h"
 #include "src/__support/StringUtil/message_mapper.h"
 #include "src/__support/integer_to_string.h"
+#include "src/errno/libc_errno.h" // For error macros
 
-#include <errno.h>
 #include <stddef.h>
 
 namespace __llvm_libc {
diff --git a/libc/src/__support/str_to_float.h b/libc/src/__support/str_to_float.h
--- a/libc/src/__support/str_to_float.h
+++ b/libc/src/__support/str_to_float.h
@@ -21,7 +21,7 @@
 #include "src/__support/high_precision_decimal.h"
 #include "src/__support/str_to_integer.h"
 #include "src/__support/str_to_num_result.h"
-#include <errno.h>
+#include "src/errno/libc_errno.h" // For ERANGE
 
 namespace __llvm_libc {
 namespace internal {
diff --git a/libc/src/__support/str_to_integer.h b/libc/src/__support/str_to_integer.h
--- a/libc/src/__support/str_to_integer.h
+++ b/libc/src/__support/str_to_integer.h
@@ -13,7 +13,7 @@
 #include "src/__support/common.h"
 #include "src/__support/ctype_utils.h"
 #include "src/__support/str_to_num_result.h"
-#include <errno.h>
+#include "src/errno/libc_errno.h" // For ERANGE
 #include <limits.h>
 
 namespace __llvm_libc {
diff --git a/libc/src/__support/threads/linux/thread.cpp b/libc/src/__support/threads/linux/thread.cpp
--- a/libc/src/__support/threads/linux/thread.cpp
+++ b/libc/src/__support/threads/linux/thread.cpp
@@ -15,12 +15,12 @@
 #include "src/__support/common.h"
 #include "src/__support/error_or.h"
 #include "src/__support/threads/linux/futex_word.h" // For FutexWordType
+#include "src/errno/libc_errno.h"                   // For error macros
 
 #ifdef LIBC_TARGET_ARCH_IS_AARCH64
 #include <arm_acle.h>
 #endif
 
-#include <errno.h>
 #include <fcntl.h>
 #include <linux/futex.h>
 #include <linux/prctl.h> // For PR_SET_NAME
diff --git a/libc/src/stdio/CMakeLists.txt b/libc/src/stdio/CMakeLists.txt
--- a/libc/src/stdio/CMakeLists.txt
+++ b/libc/src/stdio/CMakeLists.txt
@@ -25,7 +25,6 @@
     fclose.h
   DEPENDS
     libc.include.stdio
-    libc.include.errno
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
 )
@@ -109,7 +108,6 @@
   HDRS
     fgetc.h
   DEPENDS
-    libc.include.errno
     libc.include.stdio
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
@@ -122,7 +120,6 @@
   HDRS
     fgetc_unlocked.h
   DEPENDS
-    libc.include.errno
     libc.include.stdio
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
@@ -135,7 +132,6 @@
   HDRS
     getc.h
   DEPENDS
-    libc.include.errno
     libc.include.stdio
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
@@ -148,7 +144,6 @@
   HDRS
     getc_unlocked.h
   DEPENDS
-    libc.include.errno
     libc.include.stdio
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
@@ -161,7 +156,6 @@
   HDRS
     fgets.h
   DEPENDS
-    libc.include.errno
     libc.include.stdio
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
@@ -174,7 +168,6 @@
   HDRS
     fflush.h
   DEPENDS
-    libc.include.errno
     libc.include.stdio
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
@@ -211,7 +204,6 @@
   HDRS
     fread_unlocked.h
   DEPENDS
-    libc.include.errno
     libc.include.stdio
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
@@ -224,7 +216,6 @@
   HDRS
     fread.h
   DEPENDS
-    libc.include.errno
     libc.include.stdio
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
@@ -237,7 +228,6 @@
   HDRS
     fwrite_unlocked.h
   DEPENDS
-    libc.include.errno
     libc.include.stdio
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
@@ -250,7 +240,6 @@
   HDRS
     fwrite.h
   DEPENDS
-    libc.include.errno
     libc.include.stdio
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
@@ -263,7 +252,6 @@
   HDRS
     fputc.h
   DEPENDS
-    libc.include.errno
     libc.include.stdio
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
@@ -276,7 +264,6 @@
   HDRS
     putc.h
   DEPENDS
-    libc.include.errno
     libc.include.stdio
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
@@ -289,7 +276,6 @@
   HDRS
     putchar.h
   DEPENDS
-    libc.include.errno
     libc.include.stdio
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
@@ -302,7 +288,6 @@
   HDRS
     fputs.h
   DEPENDS
-    libc.include.errno
     libc.include.stdio
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
@@ -316,7 +301,6 @@
   HDRS
     puts.h
   DEPENDS
-    libc.include.errno
     libc.include.stdio
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
@@ -329,7 +313,6 @@
   HDRS
     fseek.h
   DEPENDS
-    libc.include.errno
     libc.include.stdio
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
@@ -402,7 +385,6 @@
   HDRS
     setbuf.h
   DEPENDS
-    libc.include.errno
     libc.include.stdio
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
@@ -415,7 +397,6 @@
   HDRS
     setvbuf.h
   DEPENDS
-    libc.include.errno
     libc.include.stdio
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
@@ -512,7 +493,6 @@
   HDRS
     ftell.h
   DEPENDS
-    libc.include.errno
     libc.include.stdio
     libc.src.__support.File.file
     libc.src.__support.File.platform_file
diff --git a/libc/src/stdio/fclose.cpp b/libc/src/stdio/fclose.cpp
--- a/libc/src/stdio/fclose.cpp
+++ b/libc/src/stdio/fclose.cpp
@@ -9,7 +9,7 @@
 #include "src/stdio/fclose.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stdio.h>
 
 namespace __llvm_libc {
@@ -18,7 +18,7 @@
   auto *file = reinterpret_cast<__llvm_libc::File *>(stream);
   int result = File::cleanup(file);
   if (result != 0) {
-    errno = result;
+    libc_errno = result;
     return EOF;
   }
   return 0;
diff --git a/libc/src/stdio/fflush.cpp b/libc/src/stdio/fflush.cpp
--- a/libc/src/stdio/fflush.cpp
+++ b/libc/src/stdio/fflush.cpp
@@ -9,7 +9,7 @@
 #include "src/stdio/fflush.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stdio.h>
 
 namespace __llvm_libc {
@@ -17,7 +17,7 @@
 LLVM_LIBC_FUNCTION(int, fflush, (::FILE * stream)) {
   int result = reinterpret_cast<__llvm_libc::File *>(stream)->flush();
   if (result != 0) {
-    errno = result;
+    libc_errno = result;
     return EOF;
   }
   return 0;
diff --git a/libc/src/stdio/fgetc.cpp b/libc/src/stdio/fgetc.cpp
--- a/libc/src/stdio/fgetc.cpp
+++ b/libc/src/stdio/fgetc.cpp
@@ -9,7 +9,7 @@
 #include "src/stdio/fgetc.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stdio.h>
 
 namespace __llvm_libc {
@@ -19,7 +19,7 @@
   auto result = reinterpret_cast<__llvm_libc::File *>(stream)->read(&c, 1);
   size_t r = result.value;
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
 
   if (r != 1)
     return EOF;
diff --git a/libc/src/stdio/fgetc_unlocked.cpp b/libc/src/stdio/fgetc_unlocked.cpp
--- a/libc/src/stdio/fgetc_unlocked.cpp
+++ b/libc/src/stdio/fgetc_unlocked.cpp
@@ -9,7 +9,7 @@
 #include "src/stdio/fgetc_unlocked.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stdio.h>
 
 namespace __llvm_libc {
@@ -20,7 +20,7 @@
       reinterpret_cast<__llvm_libc::File *>(stream)->read_unlocked(&c, 1);
   size_t r = result.value;
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
   if (r != 1)
     return EOF;
   return c;
diff --git a/libc/src/stdio/fgets.cpp b/libc/src/stdio/fgets.cpp
--- a/libc/src/stdio/fgets.cpp
+++ b/libc/src/stdio/fgets.cpp
@@ -9,7 +9,7 @@
 #include "src/stdio/fgets.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stddef.h>
 #include <stdio.h>
 
@@ -32,7 +32,7 @@
     auto result = stream->read_unlocked(&c, 1);
     size_t r = result.value;
     if (result.has_error())
-      errno = result.error;
+      libc_errno = result.error;
 
     if (r != 1)
       break;
diff --git a/libc/src/stdio/fopen.cpp b/libc/src/stdio/fopen.cpp
--- a/libc/src/stdio/fopen.cpp
+++ b/libc/src/stdio/fopen.cpp
@@ -9,7 +9,7 @@
 #include "src/stdio/fopen.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stdio.h>
 
 namespace __llvm_libc {
@@ -18,7 +18,7 @@
                    (const char *__restrict name, const char *__restrict mode)) {
   auto result = __llvm_libc::openfile(name, mode);
   if (!result.has_value()) {
-    errno = result.error();
+    libc_errno = result.error();
     return nullptr;
   }
   return reinterpret_cast<::FILE *>(result.value());
diff --git a/libc/src/stdio/fopencookie.cpp b/libc/src/stdio/fopencookie.cpp
--- a/libc/src/stdio/fopencookie.cpp
+++ b/libc/src/stdio/fopencookie.cpp
@@ -10,7 +10,7 @@
 #include "src/__support/CPP/new.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stdio.h>
 #include <stdlib.h>
 
diff --git a/libc/src/stdio/fputc.cpp b/libc/src/stdio/fputc.cpp
--- a/libc/src/stdio/fputc.cpp
+++ b/libc/src/stdio/fputc.cpp
@@ -9,7 +9,7 @@
 #include "src/stdio/fputc.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stdio.h>
 
 namespace __llvm_libc {
@@ -19,7 +19,7 @@
 
   auto result = reinterpret_cast<__llvm_libc::File *>(stream)->write(&uc, 1);
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
   size_t written = result.value;
 
   if (1 != written) {
diff --git a/libc/src/stdio/fputs.cpp b/libc/src/stdio/fputs.cpp
--- a/libc/src/stdio/fputs.cpp
+++ b/libc/src/stdio/fputs.cpp
@@ -10,7 +10,7 @@
 #include "src/__support/CPP/string_view.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stdio.h>
 
 namespace __llvm_libc {
@@ -22,7 +22,7 @@
   auto result = reinterpret_cast<__llvm_libc::File *>(stream)->write(
       str, str_view.size());
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
   size_t written = result.value;
 
   if (str_view.size() != written) {
diff --git a/libc/src/stdio/fread.cpp b/libc/src/stdio/fread.cpp
--- a/libc/src/stdio/fread.cpp
+++ b/libc/src/stdio/fread.cpp
@@ -9,7 +9,7 @@
 #include "src/stdio/fread.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stdio.h>
 
 namespace __llvm_libc {
@@ -22,7 +22,7 @@
   auto result =
       reinterpret_cast<__llvm_libc::File *>(stream)->read(buffer, size * nmemb);
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
   return result.value / size;
 }
 
diff --git a/libc/src/stdio/fread_unlocked.cpp b/libc/src/stdio/fread_unlocked.cpp
--- a/libc/src/stdio/fread_unlocked.cpp
+++ b/libc/src/stdio/fread_unlocked.cpp
@@ -9,7 +9,7 @@
 #include "src/stdio/fread_unlocked.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stdio.h>
 
 namespace __llvm_libc {
@@ -22,7 +22,7 @@
   auto result = reinterpret_cast<__llvm_libc::File *>(stream)->read_unlocked(
       buffer, size * nmemb);
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
   return result.value / size;
 }
 
diff --git a/libc/src/stdio/fseek.cpp b/libc/src/stdio/fseek.cpp
--- a/libc/src/stdio/fseek.cpp
+++ b/libc/src/stdio/fseek.cpp
@@ -9,7 +9,7 @@
 #include "src/stdio/fseek.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stdio.h>
 
 namespace __llvm_libc {
@@ -18,7 +18,7 @@
   auto result =
       reinterpret_cast<__llvm_libc::File *>(stream)->seek(offset, whence);
   if (!result.has_value()) {
-    errno = result.error();
+    libc_errno = result.error();
     return -1;
   }
   return 0;
diff --git a/libc/src/stdio/ftell.cpp b/libc/src/stdio/ftell.cpp
--- a/libc/src/stdio/ftell.cpp
+++ b/libc/src/stdio/ftell.cpp
@@ -9,7 +9,7 @@
 #include "src/stdio/ftell.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stdio.h>
 
 namespace __llvm_libc {
@@ -17,7 +17,7 @@
 LLVM_LIBC_FUNCTION(long, ftell, (::FILE * stream)) {
   auto result = reinterpret_cast<__llvm_libc::File *>(stream)->tell();
   if (!result.has_value()) {
-    errno = result.error();
+    libc_errno = result.error();
     return -1;
   }
   return result.value();
diff --git a/libc/src/stdio/fwrite.cpp b/libc/src/stdio/fwrite.cpp
--- a/libc/src/stdio/fwrite.cpp
+++ b/libc/src/stdio/fwrite.cpp
@@ -9,7 +9,7 @@
 #include "src/stdio/fwrite.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stdio.h>
 
 namespace __llvm_libc {
@@ -22,7 +22,7 @@
   auto result = reinterpret_cast<__llvm_libc::File *>(stream)->write(
       buffer, size * nmemb);
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
 
   return result.value / size;
 }
diff --git a/libc/src/stdio/fwrite_unlocked.cpp b/libc/src/stdio/fwrite_unlocked.cpp
--- a/libc/src/stdio/fwrite_unlocked.cpp
+++ b/libc/src/stdio/fwrite_unlocked.cpp
@@ -9,7 +9,7 @@
 #include "src/stdio/fwrite_unlocked.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stdio.h>
 
 namespace __llvm_libc {
@@ -23,7 +23,7 @@
   auto result = reinterpret_cast<__llvm_libc::File *>(stream)->write_unlocked(
       buffer, size * nmemb);
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
 
   return result.value / size;
 }
diff --git a/libc/src/stdio/getc.cpp b/libc/src/stdio/getc.cpp
--- a/libc/src/stdio/getc.cpp
+++ b/libc/src/stdio/getc.cpp
@@ -9,7 +9,7 @@
 #include "src/stdio/getc.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stdio.h>
 
 namespace __llvm_libc {
@@ -19,7 +19,7 @@
   auto result = reinterpret_cast<__llvm_libc::File *>(stream)->read(&c, 1);
   size_t r = result.value;
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
 
   if (r != 1)
     return EOF;
diff --git a/libc/src/stdio/getc_unlocked.cpp b/libc/src/stdio/getc_unlocked.cpp
--- a/libc/src/stdio/getc_unlocked.cpp
+++ b/libc/src/stdio/getc_unlocked.cpp
@@ -9,7 +9,7 @@
 #include "src/stdio/getc_unlocked.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stdio.h>
 
 namespace __llvm_libc {
@@ -20,7 +20,7 @@
       reinterpret_cast<__llvm_libc::File *>(stream)->read_unlocked(&c, 1);
   size_t r = result.value;
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
 
   if (r != 1)
     return EOF;
diff --git a/libc/src/stdio/linux/remove.cpp b/libc/src/stdio/linux/remove.cpp
--- a/libc/src/stdio/linux/remove.cpp
+++ b/libc/src/stdio/linux/remove.cpp
@@ -11,7 +11,7 @@
 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
 #include "src/__support/common.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <fcntl.h>       // For AT_* macros.
 #include <sys/syscall.h> // For syscall numbers.
 
@@ -25,7 +25,7 @@
     ret = __llvm_libc::syscall_impl(SYS_unlinkat, AT_FDCWD, path, AT_REMOVEDIR);
   if (ret >= 0)
     return 0;
-  errno = -ret;
+  libc_errno = -ret;
   return -1;
 }
 
diff --git a/libc/src/stdio/putc.cpp b/libc/src/stdio/putc.cpp
--- a/libc/src/stdio/putc.cpp
+++ b/libc/src/stdio/putc.cpp
@@ -9,7 +9,7 @@
 #include "src/stdio/putc.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stdio.h>
 
 namespace __llvm_libc {
@@ -19,7 +19,7 @@
 
   auto result = reinterpret_cast<__llvm_libc::File *>(stream)->write(&uc, 1);
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
   size_t written = result.value;
 
   if (1 != written) {
diff --git a/libc/src/stdio/putchar.cpp b/libc/src/stdio/putchar.cpp
--- a/libc/src/stdio/putchar.cpp
+++ b/libc/src/stdio/putchar.cpp
@@ -9,7 +9,7 @@
 #include "src/stdio/putchar.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stdio.h>
 
 namespace __llvm_libc {
@@ -19,7 +19,7 @@
 
   auto result = __llvm_libc::stdout->write(&uc, 1);
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
   size_t written = result.value;
 
   if (1 != written) {
diff --git a/libc/src/stdio/puts.cpp b/libc/src/stdio/puts.cpp
--- a/libc/src/stdio/puts.cpp
+++ b/libc/src/stdio/puts.cpp
@@ -10,7 +10,7 @@
 #include "src/__support/CPP/string_view.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stdio.h>
 
 namespace __llvm_libc {
@@ -19,7 +19,7 @@
   cpp::string_view str_view(str);
   auto result = __llvm_libc::stdout->write(str, str_view.size());
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
   size_t written = result.value;
   if (str_view.size() != written) {
     // The stream should be in an error state in this case.
@@ -27,7 +27,7 @@
   }
   result = __llvm_libc::stdout->write("\n", 1);
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
   written = result.value;
   if (1 != written) {
     // The stream should be in an error state in this case.
diff --git a/libc/src/stdio/setbuf.cpp b/libc/src/stdio/setbuf.cpp
--- a/libc/src/stdio/setbuf.cpp
+++ b/libc/src/stdio/setbuf.cpp
@@ -9,7 +9,7 @@
 #include "src/stdio/setbuf.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stdio.h>
 
 namespace __llvm_libc {
@@ -22,7 +22,7 @@
   int err = reinterpret_cast<__llvm_libc::File *>(stream)->set_buffer(
       buf, BUFSIZ, mode);
   if (err != 0)
-    errno = err;
+    libc_errno = err;
 }
 
 } // namespace __llvm_libc
diff --git a/libc/src/stdio/setvbuf.cpp b/libc/src/stdio/setvbuf.cpp
--- a/libc/src/stdio/setvbuf.cpp
+++ b/libc/src/stdio/setvbuf.cpp
@@ -9,7 +9,7 @@
 #include "src/stdio/setvbuf.h"
 #include "src/__support/File/file.h"
 
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 #include <stdio.h>
 
 namespace __llvm_libc {
@@ -20,7 +20,7 @@
   int err = reinterpret_cast<__llvm_libc::File *>(stream)->set_buffer(buf, size,
                                                                       type);
   if (err != 0)
-    errno = err;
+    libc_errno = err;
   return err;
 }
 
diff --git a/libc/src/stdlib/atof.cpp b/libc/src/stdlib/atof.cpp
--- a/libc/src/stdlib/atof.cpp
+++ b/libc/src/stdlib/atof.cpp
@@ -9,14 +9,14 @@
 #include "src/stdlib/atof.h"
 #include "src/__support/common.h"
 #include "src/__support/str_to_float.h"
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 
 namespace __llvm_libc {
 
 LLVM_LIBC_FUNCTION(double, atof, (const char *str)) {
   auto result = internal::strtofloatingpoint<double>(str);
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
 
   return result.value;
 }
diff --git a/libc/src/stdlib/atoi.cpp b/libc/src/stdlib/atoi.cpp
--- a/libc/src/stdlib/atoi.cpp
+++ b/libc/src/stdlib/atoi.cpp
@@ -9,6 +9,7 @@
 #include "src/stdlib/atoi.h"
 #include "src/__support/common.h"
 #include "src/__support/str_to_integer.h"
+#include "src/errno/libc_errno.h"
 
 namespace __llvm_libc {
 
@@ -17,7 +18,7 @@
   // (int)(strtol).
   auto result = internal::strtointeger<long>(str, 10);
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
 
   return static_cast<int>(result);
 }
diff --git a/libc/src/stdlib/atol.cpp b/libc/src/stdlib/atol.cpp
--- a/libc/src/stdlib/atol.cpp
+++ b/libc/src/stdlib/atol.cpp
@@ -9,13 +9,14 @@
 #include "src/stdlib/atol.h"
 #include "src/__support/common.h"
 #include "src/__support/str_to_integer.h"
+#include "src/errno/libc_errno.h"
 
 namespace __llvm_libc {
 
 LLVM_LIBC_FUNCTION(long, atol, (const char *str)) {
   auto result = internal::strtointeger<long>(str, 10);
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
 
   return result;
 }
diff --git a/libc/src/stdlib/atoll.cpp b/libc/src/stdlib/atoll.cpp
--- a/libc/src/stdlib/atoll.cpp
+++ b/libc/src/stdlib/atoll.cpp
@@ -9,13 +9,14 @@
 #include "src/stdlib/atoll.h"
 #include "src/__support/common.h"
 #include "src/__support/str_to_integer.h"
+#include "src/errno/libc_errno.h"
 
 namespace __llvm_libc {
 
 LLVM_LIBC_FUNCTION(long long, atoll, (const char *str)) {
   auto result = internal::strtointeger<long long>(str, 10);
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
 
   return result;
 }
diff --git a/libc/src/stdlib/strtod.cpp b/libc/src/stdlib/strtod.cpp
--- a/libc/src/stdlib/strtod.cpp
+++ b/libc/src/stdlib/strtod.cpp
@@ -9,7 +9,7 @@
 #include "src/stdlib/strtod.h"
 #include "src/__support/common.h"
 #include "src/__support/str_to_float.h"
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 
 namespace __llvm_libc {
 
@@ -17,7 +17,7 @@
                    (const char *__restrict str, char **__restrict str_end)) {
   auto result = internal::strtofloatingpoint<double>(str);
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
 
   if (str_end != NULL)
     *str_end = const_cast<char *>(str + result.parsed_len);
diff --git a/libc/src/stdlib/strtof.cpp b/libc/src/stdlib/strtof.cpp
--- a/libc/src/stdlib/strtof.cpp
+++ b/libc/src/stdlib/strtof.cpp
@@ -9,7 +9,7 @@
 #include "src/stdlib/strtof.h"
 #include "src/__support/common.h"
 #include "src/__support/str_to_float.h"
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 
 namespace __llvm_libc {
 
@@ -17,7 +17,7 @@
                    (const char *__restrict str, char **__restrict str_end)) {
   auto result = internal::strtofloatingpoint<float>(str);
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
 
   if (str_end != NULL)
     *str_end = const_cast<char *>(str + result.parsed_len);
diff --git a/libc/src/stdlib/strtol.cpp b/libc/src/stdlib/strtol.cpp
--- a/libc/src/stdlib/strtol.cpp
+++ b/libc/src/stdlib/strtol.cpp
@@ -9,6 +9,7 @@
 #include "src/stdlib/strtol.h"
 #include "src/__support/common.h"
 #include "src/__support/str_to_integer.h"
+#include "src/errno/libc_errno.h"
 
 namespace __llvm_libc {
 
@@ -17,7 +18,7 @@
                     int base)) {
   auto result = internal::strtointeger<long>(str, base);
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
 
   if (str_end != nullptr)
     *str_end = const_cast<char *>(str + result.parsed_len);
diff --git a/libc/src/stdlib/strtold.cpp b/libc/src/stdlib/strtold.cpp
--- a/libc/src/stdlib/strtold.cpp
+++ b/libc/src/stdlib/strtold.cpp
@@ -9,7 +9,7 @@
 #include "src/stdlib/strtold.h"
 #include "src/__support/common.h"
 #include "src/__support/str_to_float.h"
-#include <errno.h>
+#include "src/errno/libc_errno.h"
 
 namespace __llvm_libc {
 
@@ -17,7 +17,7 @@
                    (const char *__restrict str, char **__restrict str_end)) {
   auto result = internal::strtofloatingpoint<long double>(str);
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
 
   if (str_end != NULL)
     *str_end = const_cast<char *>(str + result.parsed_len);
diff --git a/libc/src/stdlib/strtoll.cpp b/libc/src/stdlib/strtoll.cpp
--- a/libc/src/stdlib/strtoll.cpp
+++ b/libc/src/stdlib/strtoll.cpp
@@ -9,6 +9,7 @@
 #include "src/stdlib/strtoll.h"
 #include "src/__support/common.h"
 #include "src/__support/str_to_integer.h"
+#include "src/errno/libc_errno.h"
 
 namespace __llvm_libc {
 
@@ -17,7 +18,7 @@
                     int base)) {
   auto result = internal::strtointeger<long long>(str, base);
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
 
   if (str_end != nullptr)
     *str_end = const_cast<char *>(str + result.parsed_len);
diff --git a/libc/src/stdlib/strtoul.cpp b/libc/src/stdlib/strtoul.cpp
--- a/libc/src/stdlib/strtoul.cpp
+++ b/libc/src/stdlib/strtoul.cpp
@@ -9,6 +9,7 @@
 #include "src/stdlib/strtoul.h"
 #include "src/__support/common.h"
 #include "src/__support/str_to_integer.h"
+#include "src/errno/libc_errno.h"
 
 namespace __llvm_libc {
 
@@ -17,7 +18,7 @@
                     int base)) {
   auto result = internal::strtointeger<unsigned long>(str, base);
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
 
   if (str_end != nullptr)
     *str_end = const_cast<char *>(str + result.parsed_len);
diff --git a/libc/src/stdlib/strtoull.cpp b/libc/src/stdlib/strtoull.cpp
--- a/libc/src/stdlib/strtoull.cpp
+++ b/libc/src/stdlib/strtoull.cpp
@@ -9,6 +9,7 @@
 #include "src/stdlib/strtoull.h"
 #include "src/__support/common.h"
 #include "src/__support/str_to_integer.h"
+#include "src/errno/libc_errno.h"
 
 namespace __llvm_libc {
 
@@ -17,7 +18,7 @@
                     int base)) {
   auto result = internal::strtointeger<unsigned long long>(str, base);
   if (result.has_error())
-    errno = result.error;
+    libc_errno = result.error;
 
   if (str_end != nullptr)
     *str_end = const_cast<char *>(str + result.parsed_len);
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
@@ -288,6 +288,7 @@
         ":__support_cpp_limits",
         ":__support_ctype_utils",
         ":__support_str_to_num_result",
+        ":errno",
     ],
 )
 
@@ -309,6 +310,7 @@
         ":__support_str_to_integer",
         ":__support_str_to_num_result",
         ":__support_uint128",
+        ":errno",
     ],
 )
 
@@ -1331,6 +1333,7 @@
     deps = [
         ":__support_common",
         ":__support_str_to_integer",
+        ":errno",
     ],
 )
 
@@ -1341,6 +1344,7 @@
     deps = [
         ":__support_common",
         ":__support_str_to_integer",
+        ":errno",
     ],
 )
 
@@ -1351,6 +1355,7 @@
     deps = [
         ":__support_common",
         ":__support_str_to_integer",
+        ":errno",
     ],
 )
 
@@ -1361,6 +1366,7 @@
     deps = [
         ":__support_common",
         ":__support_str_to_float",
+        ":errno",
     ],
 )
 
@@ -1389,6 +1395,7 @@
     deps = [
         ":__support_common",
         ":__support_str_to_integer",
+        ":errno",
     ],
 )
 
@@ -1399,6 +1406,7 @@
     deps = [
         ":__support_common",
         ":__support_str_to_integer",
+        ":errno",
     ],
 )
 
@@ -1409,6 +1417,7 @@
     deps = [
         ":__support_common",
         ":__support_str_to_integer",
+        ":errno",
     ],
 )
 
@@ -1419,6 +1428,7 @@
     deps = [
         ":__support_common",
         ":__support_str_to_integer",
+        ":errno",
     ],
 )
 
@@ -1429,6 +1439,7 @@
     deps = [
         ":__support_common",
         ":__support_str_to_float",
+        ":errno",
     ],
 )
 
@@ -1439,6 +1450,7 @@
     deps = [
         ":__support_common",
         ":__support_str_to_float",
+        ":errno",
     ],
 )
 
@@ -1449,6 +1461,7 @@
     deps = [
         ":__support_common",
         ":__support_str_to_float",
+        ":errno",
     ],
 )