diff --git a/libc/config/linux/x86_64/headers.txt b/libc/config/linux/x86_64/headers.txt
--- a/libc/config/linux/x86_64/headers.txt
+++ b/libc/config/linux/x86_64/headers.txt
@@ -6,6 +6,7 @@
     libc.include.fcntl
     libc.include.fenv
     libc.include.inttypes
+    libc.include.limits
     libc.include.math
     libc.include.pthread
     libc.include.sched
diff --git a/libc/include/CMakeLists.txt b/libc/include/CMakeLists.txt
--- a/libc/include/CMakeLists.txt
+++ b/libc/include/CMakeLists.txt
@@ -66,6 +66,15 @@
     .llvm-libc-types.imaxdiv_t
 )
 
+add_gen_header(
+  limits
+  DEF_FILE limits.h.def
+  GEN_HDR limits.h
+  DEPENDS
+    .llvm_libc_common_h
+    .llvm-libc-macros.limits_macros
+)
+
 add_gen_header(
   math
   DEF_FILE math.h.def
diff --git a/libc/include/limits.h.def b/libc/include/limits.h.def
new file mode 100644
--- /dev/null
+++ b/libc/include/limits.h.def
@@ -0,0 +1,17 @@
+//===-- C standard library header limits.h ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_LIMITS_H
+#define LLVM_LIBC_LIMITS_H
+
+#include <__llvm-libc-common.h>
+#include <llvm-libc-macros/limits-macros.h>
+
+%%public_api()
+
+#endif // LLVM_LIBC_LIMITS_H
diff --git a/libc/include/llvm-libc-macros/CMakeLists.txt b/libc/include/llvm-libc-macros/CMakeLists.txt
--- a/libc/include/llvm-libc-macros/CMakeLists.txt
+++ b/libc/include/llvm-libc-macros/CMakeLists.txt
@@ -172,3 +172,9 @@
   HDR
     wchar-macros.h
 )
+
+add_header(
+  limits_macros
+  HDR
+    limits-macros.h
+)
diff --git a/libc/include/llvm-libc-macros/limits-macros.h b/libc/include/llvm-libc-macros/limits-macros.h
new file mode 100644
--- /dev/null
+++ b/libc/include/llvm-libc-macros/limits-macros.h
@@ -0,0 +1,12 @@
+#ifndef __LLVM_LIBC_MACROS_LIMITS_MACROS_H
+#define __LLVM_LIBC_MACROS_LIMITS_MACROS_H
+
+#ifdef __linux__
+#include <linux/limits.h>
+#endif
+
+#ifndef SSIZE_MAX
+#define SSIZE_MAX __LONG_MAX__
+#endif
+
+#endif // __LLVM_LIBC_MACROS_LIMITS_MACROS_H
diff --git a/libc/spec/posix.td b/libc/spec/posix.td
--- a/libc/spec/posix.td
+++ b/libc/spec/posix.td
@@ -225,6 +225,16 @@
     ]
   >;
 
+  HeaderSpec Limits = HeaderSpec<
+    "limits.h",
+    [
+        Macro<"SSIZE_MAX">,
+    ],
+    [], // Types
+    [], // Enumerations
+    [] // Functions
+  >;
+
   HeaderSpec SysMMan = HeaderSpec<
       "sys/mman.h",
       [
@@ -1395,6 +1405,7 @@
     Dirent,
     Errno,
     FCntl,
+    Limits,
     PThread,
     Sched,
     Signal,
diff --git a/libc/spec/stdc.td b/libc/spec/stdc.td
--- a/libc/spec/stdc.td
+++ b/libc/spec/stdc.td
@@ -821,6 +821,16 @@
       ]
   >;
 
+  HeaderSpec Limits = HeaderSpec<
+      "limits.h",
+      [
+        Macro<"LONG_MAX">,
+      ],
+      [], // Types
+      [], // Enumerations
+      [] // Functions
+  >;
+
   HeaderSpec Errno = HeaderSpec<
       "errno.h",
       [
@@ -1138,6 +1148,7 @@
     StdIO,
     StdLib,
     IntTypes,
+    Limits,
     SetJmp,
     Signal,
     Threads,