diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index 48b7ca45157a6..12a108134a531 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -1082,6 +1082,7 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.stdlib.getenv
     libc.src.stdlib.ignore_handler_s
     libc.src.stdlib.quick_exit
+    libc.src.stdlib.set_constraint_handler_s
 
     # signal.h entrypoints
     libc.src.signal.kill
diff --git a/libc/config/linux/riscv/entrypoints.txt b/libc/config/linux/riscv/entrypoints.txt
index 0d3ff77d29b74..985d7fed577e9 100644
--- a/libc/config/linux/riscv/entrypoints.txt
+++ b/libc/config/linux/riscv/entrypoints.txt
@@ -1209,6 +1209,7 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.stdlib.getenv
     libc.src.stdlib.ignore_handler_s
     libc.src.stdlib.quick_exit
+    libc.src.stdlib.set_constraint_handler_s
 
     # signal.h entrypoints
     libc.src.signal.kill
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index dd94ffb30fa9a..f02f4ab80d952 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -1248,6 +1248,7 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.stdlib.getenv
     libc.src.stdlib.ignore_handler_s
     libc.src.stdlib.quick_exit
+    libc.src.stdlib.set_constraint_handler_s
 
     # signal.h entrypoints
     libc.src.signal.kill
diff --git a/libc/include/stdlib.yaml b/libc/include/stdlib.yaml
index 7c3b113a62415..49d45f105fe7a 100644
--- a/libc/include/stdlib.yaml
+++ b/libc/include/stdlib.yaml
@@ -202,6 +202,13 @@ functions:
       - type: void *__restrict
       - type: errno_t
     guard: 'LIBC_HAS_ANNEX_K'
+  - name: set_constraint_handler_s
+    standards:
+      - stdc
+    return_type: constraint_handler_t
+    arguments:
+      - type: constraint_handler_t
+    guard: 'LIBC_HAS_ANNEX_K'
   - name: srand
     standards:
       - stdc
diff --git a/libc/src/__support/annex_k/CMakeLists.txt b/libc/src/__support/annex_k/CMakeLists.txt
index 4ef4e32ebdd85..f9c067753b6e6 100644
--- a/libc/src/__support/annex_k/CMakeLists.txt
+++ b/libc/src/__support/annex_k/CMakeLists.txt
@@ -28,3 +28,11 @@ add_header_library(
     .abort_handler_s
     libc.hdr.types.constraint_handler_t
 )
+
+add_header_library(
+  set_constraint_handler_s
+  HDRS
+    set_constraint_handler_s.h
+  DEPENDS
+    
+)
diff --git a/libc/src/stdlib/CMakeLists.txt b/libc/src/stdlib/CMakeLists.txt
index 5efd7f13ff3ee..c380657300cfe 100644
--- a/libc/src/stdlib/CMakeLists.txt
+++ b/libc/src/stdlib/CMakeLists.txt
@@ -664,6 +664,17 @@ add_entrypoint_object(
     .${LIBC_TARGET_OS}.system
 )
 
+add_entrypoint_object(
+  set_constraint_handler_s
+  SRCS
+    set_constraint_handler_s.cpp
+  HDRS
+    set_constraint_handler_s.h
+  DEPENDS
+    libc.src.__support.annex_k.abort_handler_s
+    libc.src.__support.annex_k.libc_constraint_handler
+)
+
 add_entrypoint_object(
   ignore_handler_s
   HDRS
diff --git a/libc/src/stdlib/set_constraint_handler_s.cpp b/libc/src/stdlib/set_constraint_handler_s.cpp
new file mode 100644
index 0000000000000..d3a16d77e3b0a
--- /dev/null
+++ b/libc/src/stdlib/set_constraint_handler_s.cpp
@@ -0,0 +1,28 @@
+//===-- Implementation of set_constraint_handler_s ------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "set_constraint_handler_s.h"
+#include "src/__support/annex_k/abort_handler_s.h"
+#include "src/__support/annex_k/libc_constraint_handler.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(constraint_handler_t, set_constraint_handler_s,
+                   (constraint_handler_t handler)) {
+  auto previous_handler = annex_k::libc_constraint_handler;
+
+  if (!handler) {
+    annex_k::libc_constraint_handler = &annex_k::abort_handler_s;
+  } else {
+    annex_k::libc_constraint_handler = handler;
+  }
+
+  return previous_handler;
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/stdlib/set_constraint_handler_s.h b/libc/src/stdlib/set_constraint_handler_s.h
new file mode 100644
index 0000000000000..f5c6e01712ef0
--- /dev/null
+++ b/libc/src/stdlib/set_constraint_handler_s.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for set_constraint_handler_s ------*- C++ -*-===//
+//
+// 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_SRC_STDLIB_SET_CONSTRAINT_HANDLER_S_H
+#define LLVM_LIBC_SRC_STDLIB_SET_CONSTRAINT_HANDLER_S_H
+
+#include "hdr/types/constraint_handler_t.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+constraint_handler_t set_constraint_handler_s(constraint_handler_t handler);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_STDLIB_SET_CONSTRAINT_HANDLER_S_H