diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -34,6 +34,7 @@
     libc.src.string.strcmp
     libc.src.string.strcpy
     libc.src.string.strcspn
+    libc.src.string.strdup
     libc.src.string.strlen
     libc.src.string.strncmp
     libc.src.string.strncpy
@@ -182,6 +183,11 @@
     libc.src.stdlib._Exit
     libc.src.stdlib.abort
 
+#    libc.src.stdlib.malloc
+#    libc.src.stdlib.calloc
+#    libc.src.stdlib.realloc
+#    libc.src.stdlib.free
+
     # signal.h entrypoints
     libc.src.signal.raise
     libc.src.signal.sigaction
diff --git a/libc/include/stdlib.h.def b/libc/include/stdlib.h.def
--- a/libc/include/stdlib.h.def
+++ b/libc/include/stdlib.h.def
@@ -13,4 +13,12 @@
 
 %%public_api()
 
+
+__BEGIN_C_DECLS
+  void* malloc(size_t);
+  void* calloc(size_t, size_t);
+  void* realloc(void*, size_t);
+  void free(void*);
+__END_C_DECLS
+
 #endif // LLVM_LIBC_STDLIB_H
diff --git a/libc/spec/stdc.td b/libc/spec/stdc.td
--- a/libc/spec/stdc.td
+++ b/libc/spec/stdc.td
@@ -279,6 +279,11 @@
               RetValSpec<SizeTType>,
               [ArgSpec<ConstCharPtr>, ArgSpec<ConstCharPtr>]
           >,
+          FunctionSpec<
+              "strdup",
+              RetValSpec<CharPtr>,
+              [ArgSpec<ConstCharPtr>]
+          >,
           FunctionSpec<
               "strpbrk",
               RetValSpec<CharPtr>,
@@ -510,6 +515,11 @@
           FunctionSpec<"strtoul", RetValSpec<UnsignedLongType>, [ArgSpec<ConstCharRestrictedPtr>, ArgSpec<CharRestrictedPtrPtr>, ArgSpec<IntType>]>,
           FunctionSpec<"strtoull", RetValSpec<UnsignedLongLongType>, [ArgSpec<ConstCharRestrictedPtr>, ArgSpec<CharRestrictedPtrPtr>, ArgSpec<IntType>]>,
 
+          FunctionSpec<"malloc", RetValSpec<VoidPtr>, [ArgSpec<SizeTType>]>,
+          FunctionSpec<"calloc", RetValSpec<VoidPtr>, [ArgSpec<SizeTType>, ArgSpec<SizeTType>]>,
+          FunctionSpec<"realloc", RetValSpec<VoidPtr>, [ArgSpec<VoidPtr>, ArgSpec<SizeTType>]>,
+          FunctionSpec<"free", RetValSpec<VoidType>, [ArgSpec<VoidPtr>]>,
+
           FunctionSpec<"_Exit", RetValSpec<NoReturn>, [ArgSpec<IntType>]>,
       ]
   >;
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
@@ -85,6 +85,18 @@
     .string_utils
 )
 
+add_entrypoint_object(
+  strdup
+  SRCS
+    strdup.cpp
+  HDRS
+    strdup.h
+  DEPENDS
+    .memcpy
+    .string_utils
+    libc.include.stdlib
+)
+
 add_entrypoint_object(
   strlen
   SRCS
diff --git a/libc/src/string/strdup.h b/libc/src/string/strdup.h
new file mode 100644
--- /dev/null
+++ b/libc/src/string/strdup.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for strdup ------------------------*- 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_STRING_STRDUP_H
+#define LLVM_LIBC_SRC_STRING_STRDUP_H
+
+#include <string.h>
+
+namespace __llvm_libc {
+
+char *strdup(const char *src);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_STRING_STRDUP_H
diff --git a/libc/src/string/strdup.cpp b/libc/src/string/strdup.cpp
new file mode 100644
--- /dev/null
+++ b/libc/src/string/strdup.cpp
@@ -0,0 +1,30 @@
+//===-- Implementation of strdup ------------------------------------------===//
+//
+// 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 "src/string/strdup.h"
+#include "src/string/memcpy.h"
+#include "src/string/string_utils.h"
+
+#include "src/__support/common.h"
+
+#include <stdlib.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(char *, strdup, (const char *src)) {
+  size_t len = internal::string_length(src) + 1;
+  char *newStr = reinterpret_cast<char *>(::malloc(len)); // NOLINT
+  if (newStr == nullptr) {
+    return nullptr;
+  }
+  char *result =
+      reinterpret_cast<char *>(__llvm_libc::memcpy(newStr, src, len));
+  return result;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/test/src/string/CMakeLists.txt b/libc/test/src/string/CMakeLists.txt
--- a/libc/test/src/string/CMakeLists.txt
+++ b/libc/test/src/string/CMakeLists.txt
@@ -72,6 +72,17 @@
     libc.src.string.strcspn
 )
 
+add_libc_unittest(
+  strdup_test
+  SUITE
+    libc_string_unittests
+  SRCS
+  strdup_test.cpp
+  DEPENDS
+    libc.include.stdlib
+    libc.src.string.strdup
+)
+
 add_libc_unittest(
   strlen_test
   SUITE
diff --git a/libc/test/src/string/strdup_test.cpp b/libc/test/src/string/strdup_test.cpp
new file mode 100644
--- /dev/null
+++ b/libc/test/src/string/strdup_test.cpp
@@ -0,0 +1,30 @@
+//===-- Unittests for strdup ----------------------------------------------===//
+//
+// 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 "src/string/strdup.h"
+#include "utils/UnitTest/Test.h"
+#include <stdlib.h>
+
+TEST(LlvmLibcStrDupTest, EmptyString) {
+  const char *empty = "";
+
+  char *result = __llvm_libc::strdup(empty);
+  ASSERT_NE(result, static_cast<char *>(nullptr));
+  ASSERT_STREQ(empty, result);
+  ::free(result);
+}
+
+TEST(LlvmLibcStrDupTest, AnyString) {
+  const char *abc = "abc";
+
+  char *result = __llvm_libc::strdup(abc);
+
+  ASSERT_NE(result, static_cast<char *>(nullptr));
+  ASSERT_STREQ(abc, result);
+  ::free(result);
+}