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
@@ -26,6 +26,14 @@
     libc.src.sched.sched_getaffinity
     libc.src.sched.sched_setaffinity
 
+    # search.h entrypoints
+    libc.src.search.hcreate
+    libc.src.search.hcreate_r
+    libc.src.search.hdestroy
+    libc.src.search.hdestroy_r
+    libc.src.search.hsearch
+    libc.src.search.hsearch_r
+
     # string.h entrypoints
     libc.src.string.bcmp
     libc.src.string.bzero
diff --git a/libc/src/CMakeLists.txt b/libc/src/CMakeLists.txt
--- a/libc/src/CMakeLists.txt
+++ b/libc/src/CMakeLists.txt
@@ -8,6 +8,7 @@
 add_subdirectory(string)
 add_subdirectory(stdlib)
 add_subdirectory(stdio)
+add_subdirectory(search)
 
 if(${LIBC_TARGET_OS} STREQUAL "linux")
   add_subdirectory(dirent)
diff --git a/libc/src/search/CMakeLists.txt b/libc/src/search/CMakeLists.txt
new file mode 100644
--- /dev/null
+++ b/libc/src/search/CMakeLists.txt
@@ -0,0 +1,68 @@
+add_subdirectory(hashtable)
+
+add_entrypoint_object(
+  hsearch
+  SRCS
+    hsearch.cpp
+  HDRS 
+    hsearch.h
+  DEPENDS
+    .hashtable.global
+    .hashtable.search_impl
+)
+
+add_entrypoint_object(
+  hsearch_r
+  SRCS
+    hsearch_r.cpp
+  HDRS 
+    hsearch_r.h
+  DEPENDS
+    .hashtable.search_impl
+)
+
+add_entrypoint_object(
+  hcreate
+  SRCS
+    hcreate.cpp
+  HDRS 
+    hcreate.h
+  DEPENDS
+    .hashtable.global
+    .hashtable.utils
+    libc.include.errno
+)
+
+add_entrypoint_object(
+  hcreate_r
+  SRCS
+    hcreate_r.cpp
+  HDRS 
+    hcreate_r.h
+  DEPENDS
+    .hashtable.utils
+    libc.include.stdlib
+    libc.include.errno
+)
+
+add_entrypoint_object(
+  hdestroy
+  SRCS
+  hdestroy.cpp
+  HDRS 
+  hdestroy.h
+  DEPENDS
+    .hashtable.global
+    .hashtable.utils
+)
+
+add_entrypoint_object(
+  hdestroy_r
+  SRCS
+    hdestroy_r.cpp
+  HDRS 
+    hdestroy_r.h
+  DEPENDS
+    .hashtable.utils
+    libc.include.stdlib
+)
diff --git a/libc/src/search/hashtable/CMakeLists.txt b/libc/src/search/hashtable/CMakeLists.txt
new file mode 100644
--- /dev/null
+++ b/libc/src/search/hashtable/CMakeLists.txt
@@ -0,0 +1,30 @@
+add_header_library(
+  utils
+  HDRS
+    utils.h
+  DEPENDS
+    libc.src.__support.wyhash
+    libc.src.__support.swisstable
+    libc.src.string.strcmp
+    libc.src.string.strlen
+    libc.include.search
+)
+
+add_object_library(
+  global
+  SRCS
+    global.cpp 
+  HDRS
+    global.h
+  DEPENDS
+    .utils
+)
+
+add_header_library(
+  search_impl
+  HDRS
+    search_impl.h
+  DEPENDS
+    .utils
+    libc.include.errno
+)
diff --git a/libc/src/search/hashtable/global.h b/libc/src/search/hashtable/global.h
new file mode 100644
--- /dev/null
+++ b/libc/src/search/hashtable/global.h
@@ -0,0 +1,18 @@
+//===-- Implementation Header of Global Hashtable -------------------------===//
+//
+// 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_SEARCH_HASHTABLE_GLOBAL_H
+#define LLVM_LIBC_SRC_SEARCH_HASHTABLE_GLOBAL_H
+
+#include "src/search/hashtable/utils.h"
+
+namespace __llvm_libc::search::hashtable {
+extern SeededTable global_raw_table;
+} // namespace __llvm_libc::search::hashtable
+
+#endif // LLVM_LIBC_SRC_SEARCH_HASHTABLE_GLOBAL_H
diff --git a/libc/src/search/hashtable/global.cpp b/libc/src/search/hashtable/global.cpp
new file mode 100644
--- /dev/null
+++ b/libc/src/search/hashtable/global.cpp
@@ -0,0 +1,13 @@
+//===-- Implementation of Global Hashtable --------------------------------===//
+//
+// 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/search/hashtable/global.h"
+
+namespace __llvm_libc::search::hashtable {
+SeededTable global_raw_table;
+}
diff --git a/libc/src/search/hashtable/search_impl.h b/libc/src/search/hashtable/search_impl.h
new file mode 100644
--- /dev/null
+++ b/libc/src/search/hashtable/search_impl.h
@@ -0,0 +1,45 @@
+//===-- Implementation Header of Hashtable Search  -------------------  ---===//
+//
+// 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_SEARCH_HASHTABLE_SEARCH_IMPL_H
+#define LLVM_LIBC_SRC_SEARCH_HASHTABLE_SEARCH_IMPL_H
+
+#include "src/search/hashtable/utils.h"
+#include <errno.h>
+namespace __llvm_libc::search::hashtable {
+
+static inline int search_impl(ENTRY item, ACTION action, ENTRY **retval,
+                              SeededTable *table) {
+  using namespace search;
+  Hash hasher{table->seed};
+  switch (action) {
+  case ENTER: {
+    auto bucket = table->raw.find_or_insert(item, hasher, equal);
+    if (!bucket) {
+      *retval = nullptr;
+      errno = ENOMEM;
+      return 0;
+    }
+    *retval = bucket.ptr - 1;
+    return 1;
+  }
+  case FIND: {
+    auto bucket = table->raw.find(item, hasher, equal);
+    if (!bucket) {
+      *retval = nullptr;
+      errno = ESRCH;
+      return 0;
+    }
+    *retval = bucket.ptr - 1;
+    return 1;
+  }
+  }
+
+  return 0;
+}
+} // namespace __llvm_libc::search::hashtable
+#endif // LLVM_LIBC_SRC_SEARCH_HASHTABLE_SEARCH_IMPL_H
diff --git a/libc/src/search/hashtable/utils.h b/libc/src/search/hashtable/utils.h
new file mode 100644
--- /dev/null
+++ b/libc/src/search/hashtable/utils.h
@@ -0,0 +1,68 @@
+//===-- Utilities of hashtable --------------------------------------------===//
+//
+// 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_SEARCH_HASHTABLE_UTILS_H
+#define LLVM_LIBC_SRC_SEARCH_HASHTABLE_UTILS_H
+
+#ifndef LLVM_LIBC_SEARCH_ENABLE_HASHTABLE_RESIZE
+#define LLVM_LIBC_SEARCH_ENABLE_HASHTABLE_RESIZE 0
+#endif
+
+#ifndef LLVM_LIBC_SEARCH_ENABLE_HASHTABLE_DELETION
+#define LLVM_LIBC_SEARCH_ENABLE_HASHTABLE_DELETION 0
+#endif
+
+#include "src/__support/swisstable.h"
+#include "src/__support/wyhash.h"
+#include "src/string/strcmp.h"
+#include "src/string/strlen.h"
+#include <search.h>
+
+namespace __llvm_libc::search::hashtable {
+
+static inline bool equal(const ENTRY &a, const ENTRY &b) {
+  return strcmp(a.key, b.key) == 0;
+}
+
+using RawTable =
+    cpp::swisstable::RawTable<ENTRY, LLVM_LIBC_SEARCH_ENABLE_HASHTABLE_RESIZE,
+                              LLVM_LIBC_SEARCH_ENABLE_HASHTABLE_DELETION>;
+
+struct SeededTable {
+  RawTable raw;
+  uint64_t seed;
+};
+
+using Bucket = cpp::swisstable::Bucket<ENTRY>;
+
+struct TableHeader {
+  SeededTable *table;
+};
+
+static inline SeededTable *get_table(hsearch_data *hdata) {
+  return reinterpret_cast<TableHeader *>(hdata)->table;
+}
+
+static inline void set_table(hsearch_data *hdata, SeededTable *table) {
+  reinterpret_cast<TableHeader *>(hdata)->table = table;
+}
+
+struct Hash {
+  uint64_t seed;
+  uint64_t operator()(const ENTRY &entry) const {
+    size_t length = __llvm_libc::strlen(entry.key);
+    return cpp::wyhash::DefaultHash::hash(entry.key, length, seed);
+  }
+};
+
+// For now, we use only for seed to initialize the table.
+// The number comes from Kunth's PRNG.
+static constexpr inline uint64_t DEFAULT_SEED = 6364136223846793005;
+
+} // namespace __llvm_libc::search::hashtable
+#endif // LLVM_LIBC_SRC_SEARCH_HASHTABLE_UTILS_H
diff --git a/libc/src/search/hcreate.h b/libc/src/search/hcreate.h
new file mode 100644
--- /dev/null
+++ b/libc/src/search/hcreate.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for hcreate -----------------------*- 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_SEARCH_HCREATE_H
+#define LLVM_LIBC_SRC_SEARCH_HCREATE_H
+
+#include <search.h>
+
+namespace __llvm_libc {
+int hcreate(size_t);
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_SEARCH_HCREATE_H
diff --git a/libc/src/search/hcreate.cpp b/libc/src/search/hcreate.cpp
new file mode 100644
--- /dev/null
+++ b/libc/src/search/hcreate.cpp
@@ -0,0 +1,26 @@
+//===-- Implementation of hcreate -------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/search/hcreate.h"
+#include "src/search/hashtable/global.h"
+#include "src/search/hashtable/utils.h"
+#include <errno.h>
+
+namespace __llvm_libc {
+LLVM_LIBC_FUNCTION(int, hcreate, (size_t nel)) {
+  using namespace search::hashtable;
+  global_raw_table.raw = RawTable::with_capacity(nel);
+  global_raw_table.seed = DEFAULT_SEED ^ reinterpret_cast<uintptr_t>(&nel);
+  if (!global_raw_table.raw.is_valid()) {
+    errno = ENOMEM;
+    return 0;
+  }
+  return 1;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/search/hcreate_r.h b/libc/src/search/hcreate_r.h
new file mode 100644
--- /dev/null
+++ b/libc/src/search/hcreate_r.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for hcreate_r ---------------------*- 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_SEARCH_HCREATE_R_H
+#define LLVM_LIBC_SRC_SEARCH_HCREATE_R_H
+
+#include <search.h> // ENTRY, ACTION, hsearch_data
+
+namespace __llvm_libc {
+int hcreate_r(size_t, hsearch_data *);
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_SEARCH_HCREATE_R_H
diff --git a/libc/src/search/hcreate_r.cpp b/libc/src/search/hcreate_r.cpp
new file mode 100644
--- /dev/null
+++ b/libc/src/search/hcreate_r.cpp
@@ -0,0 +1,45 @@
+//===-- Implementation of hcreate_r -----------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/search/hcreate_r.h"
+#include "src/search/hashtable/utils.h"
+#include <asm-generic/errno-base.h>
+#include <errno.h>
+#include <stdlib.h>
+
+namespace __llvm_libc {
+LLVM_LIBC_FUNCTION(int, hcreate_r, (size_t nel, hsearch_data *hdata)) {
+  using namespace search::hashtable;
+
+  if (hdata == nullptr) {
+    errno = EINVAL;
+    return 0;
+  }
+
+  SeededTable *table = static_cast<SeededTable *>(
+      aligned_alloc(alignof(SeededTable), sizeof(SeededTable)));
+
+  if (table == nullptr) {
+    errno = ENOMEM;
+    return 0;
+  }
+
+  table->raw = RawTable::with_capacity(nel);
+
+  if (!table->raw.is_valid()) {
+    free(table);
+    errno = ENOMEM;
+    return 0;
+  }
+
+  set_table(hdata, table);
+  table->seed = DEFAULT_SEED ^ reinterpret_cast<uintptr_t>(table);
+  return 1;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/search/hdestroy.h b/libc/src/search/hdestroy.h
new file mode 100644
--- /dev/null
+++ b/libc/src/search/hdestroy.h
@@ -0,0 +1,16 @@
+//===-- Implementation header for hdestroy ----------------------*- 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_SEARCH_HDESTROY_H
+#define LLVM_LIBC_SRC_SEARCH_HDESTROY_H
+
+namespace __llvm_libc {
+void hdestroy();
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_SEARCH_HDESTROY_H
diff --git a/libc/src/search/hdestroy.cpp b/libc/src/search/hdestroy.cpp
new file mode 100644
--- /dev/null
+++ b/libc/src/search/hdestroy.cpp
@@ -0,0 +1,18 @@
+//===-- Implementation of hdestroy ------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/search/hdestroy.h"
+#include "src/search/hashtable/global.h"
+namespace __llvm_libc {
+LLVM_LIBC_FUNCTION(void, hdestroy, ()) {
+  using namespace search::hashtable;
+  global_raw_table.raw.release();
+  global_raw_table.seed = 0;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/search/hdestroy_r.h b/libc/src/search/hdestroy_r.h
new file mode 100644
--- /dev/null
+++ b/libc/src/search/hdestroy_r.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for hdestroy_r --------------------*- 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_SEARCH_HDESTROY_R_H
+#define LLVM_LIBC_SRC_SEARCH_HDESTROY_R_H
+
+#include <search.h>
+
+namespace __llvm_libc {
+void hdestroy_r(hsearch_data *);
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_SEARCH_HDESTROY_R_H
diff --git a/libc/src/search/hdestroy_r.cpp b/libc/src/search/hdestroy_r.cpp
new file mode 100644
--- /dev/null
+++ b/libc/src/search/hdestroy_r.cpp
@@ -0,0 +1,21 @@
+//===-- Implementation of hdestroy_r ----------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/search/hdestroy_r.h"
+#include "src/search/hashtable/utils.h"
+#include <search.h>
+namespace __llvm_libc {
+LLVM_LIBC_FUNCTION(void, hdestroy_r, (hsearch_data * hdata)) {
+  using namespace search::hashtable;
+  SeededTable *table = get_table(hdata);
+  table->raw.release();
+  table->seed = 0;
+  free(table);
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/search/hsearch.h b/libc/src/search/hsearch.h
new file mode 100644
--- /dev/null
+++ b/libc/src/search/hsearch.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for hsearch -----------------------*- 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_SEARCH_HSEARCH_H
+#define LLVM_LIBC_SRC_SEARCH_HSEARCH_H
+
+#include <search.h> // ENTRY, ACTION, hsearch_data
+
+namespace __llvm_libc {
+ENTRY *hsearch(ENTRY item, ACTION action);
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_SEARCH_HSEARCH_H
diff --git a/libc/src/search/hsearch.cpp b/libc/src/search/hsearch.cpp
new file mode 100644
--- /dev/null
+++ b/libc/src/search/hsearch.cpp
@@ -0,0 +1,21 @@
+//===-- Implementation of hsearch -------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/search/hsearch.h"
+#include "src/search/hashtable/global.h"
+#include "src/search/hashtable/search_impl.h"
+
+namespace __llvm_libc {
+LLVM_LIBC_FUNCTION(ENTRY *, hsearch, (ENTRY item, ACTION action)) {
+  using namespace search::hashtable;
+  ENTRY *e;
+  search_impl(item, action, &e, &global_raw_table);
+  return e;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/search/hsearch_r.h b/libc/src/search/hsearch_r.h
new file mode 100644
--- /dev/null
+++ b/libc/src/search/hsearch_r.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for hsearch_r ---------------------*- 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_SEARCH_HSEARCH_R_H
+#define LLVM_LIBC_SRC_SEARCH_HSEARCH_R_H
+
+#include <search.h> // ENTRY, ACTION, hsearch_data
+
+namespace __llvm_libc {
+int hsearch_r(ENTRY item, ACTION action, ENTRY **retval, hsearch_data *);
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_SEARCH_HSEARCH_R_H
diff --git a/libc/src/search/hsearch_r.cpp b/libc/src/search/hsearch_r.cpp
new file mode 100644
--- /dev/null
+++ b/libc/src/search/hsearch_r.cpp
@@ -0,0 +1,20 @@
+//===-- Implementation of hsearch_r -----------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/search/hsearch_r.h"
+#include "src/search/hashtable/search_impl.h"
+
+namespace __llvm_libc {
+LLVM_LIBC_FUNCTION(int, hsearch_r,
+                   (ENTRY item, ACTION action, ENTRY **retval,
+                    hsearch_data *hdata)) {
+  using namespace search::hashtable;
+  return search_impl(item, action, retval, get_table(hdata));
+}
+
+} // namespace __llvm_libc
diff --git a/libc/test/src/CMakeLists.txt b/libc/test/src/CMakeLists.txt
--- a/libc/test/src/CMakeLists.txt
+++ b/libc/test/src/CMakeLists.txt
@@ -32,6 +32,7 @@
 add_subdirectory(fenv)
 add_subdirectory(inttypes)
 add_subdirectory(math)
+add_subdirectory(search)
 add_subdirectory(string)
 add_subdirectory(stdlib)
 add_subdirectory(stdio)
diff --git a/libc/test/src/search/CMakeLists.txt b/libc/test/src/search/CMakeLists.txt
new file mode 100644
--- /dev/null
+++ b/libc/test/src/search/CMakeLists.txt
@@ -0,0 +1,16 @@
+add_libc_testsuite(libc_search_unittests)
+add_libc_unittest(
+  hsearch_test
+  SUITE
+    libc_search_unittests
+  SRCS
+    hsearch_test.cpp
+  DEPENDS
+    libc.src.search.hsearch_r
+    libc.src.search.hcreate_r
+    libc.src.search.hdestroy_r
+    libc.src.search.hsearch
+    libc.src.search.hcreate
+    libc.src.search.hdestroy
+    libc.src.errno.errno
+)
\ No newline at end of file
diff --git a/libc/test/src/search/hsearch_test.cpp b/libc/test/src/search/hsearch_test.cpp
new file mode 100644
--- /dev/null
+++ b/libc/test/src/search/hsearch_test.cpp
@@ -0,0 +1,117 @@
+//===-- Unittests for hsearch ---------------------------------------------===//
+//
+// 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 "llvm-libc-types/struct_hsearch_data.h"
+#include "src/search/hcreate.h"
+#include "src/search/hcreate_r.h"
+#include "src/search/hdestroy.h"
+#include "src/search/hdestroy_r.h"
+#include "src/search/hsearch.h"
+#include "test/ErrnoSetterMatcher.h"
+#include "utils/UnitTest/LibcTest.h"
+#include <asm-generic/errno-base.h>
+
+TEST(LlvmLibcHsearchTest, CreateTooLarge) {
+  using __llvm_libc::testing::ErrnoSetterMatcher::Fails;
+  struct hsearch_data hdata;
+  ASSERT_THAT(__llvm_libc::hcreate(-1), Fails(ENOMEM, 0));
+  ASSERT_THAT(__llvm_libc::hcreate_r(-1, &hdata), Fails(ENOMEM, 0));
+}
+
+TEST(LlvmLibcHSearchTest, CreateInvalid) {
+  using __llvm_libc::testing::ErrnoSetterMatcher::Fails;
+  ASSERT_THAT(__llvm_libc::hcreate_r(16, nullptr), Fails(EINVAL, 0));
+}
+
+TEST(LlvmLibcHSearchTest, CreateValid) {
+  struct hsearch_data hdata;
+  ASSERT_GT(__llvm_libc::hcreate_r(16, &hdata), 0);
+  hdestroy_r(&hdata);
+
+  ASSERT_GT(__llvm_libc::hcreate(16), 0);
+  hdestroy();
+}
+
+char search_data[] = "1234567890abcdefghijklmnopqrstuvwxyz"
+                     "1234567890abcdefghijklmnopqrstuvwxyz"
+                     "1234567890abcdefghijklmnopqrstuvwxyz"
+                     "1234567890abcdefghijklmnopqrstuvwxyz"
+                     "1234567890abcdefghijklmnopqrstuvwxyz";
+char search_data2[] =
+    "@@@@@@@@@@@@@@!!!!!!!!!!!!!!!!!###########$$$$$$$$$$^^^^^^&&&&&&&&";
+
+TEST(LlvmLibcHSearchTest, InsertTooMany) {
+  using __llvm_libc::testing::ErrnoSetterMatcher::Fails;
+  ASSERT_GT(__llvm_libc::hcreate(16), 0);
+  for (size_t i = 0; i < 16 * 7; ++i) {
+    ASSERT_EQ(__llvm_libc::hsearch({&search_data[i], nullptr}, ENTER)->key,
+              &search_data[i]);
+  }
+  ASSERT_THAT(
+      static_cast<void *>(__llvm_libc::hsearch({search_data2, nullptr}, ENTER)),
+      Fails(ENOMEM, static_cast<void *>(nullptr)));
+  hdestroy();
+}
+
+TEST(LlvmLibcHSearchTest, NotFound) {
+  using __llvm_libc::testing::ErrnoSetterMatcher::Fails;
+  ASSERT_GT(__llvm_libc::hcreate(16), 0);
+  ASSERT_THAT(
+      static_cast<void *>(__llvm_libc::hsearch({search_data2, nullptr}, FIND)),
+      Fails(ESRCH, static_cast<void *>(nullptr)));
+  for (size_t i = 0; i < 16 * 7; ++i) {
+    ASSERT_EQ(__llvm_libc::hsearch({&search_data[i], nullptr}, ENTER)->key,
+              &search_data[i]);
+  }
+  ASSERT_THAT(
+      static_cast<void *>(__llvm_libc::hsearch({search_data2, nullptr}, FIND)),
+      Fails(ESRCH, static_cast<void *>(nullptr)));
+  hdestroy();
+}
+
+TEST(LlvmLibcHSearchTest, Found) {
+  using __llvm_libc::testing::ErrnoSetterMatcher::Fails;
+  ASSERT_GT(__llvm_libc::hcreate(16), 0);
+  for (size_t i = 0; i < 16 * 7; ++i) {
+    ASSERT_EQ(__llvm_libc::hsearch(
+                  {&search_data[i], reinterpret_cast<void *>(i)}, ENTER)
+                  ->key,
+              &search_data[i]);
+  }
+  for (size_t i = 0; i < 16 * 7; ++i) {
+    ASSERT_EQ(__llvm_libc::hsearch({&search_data[i], nullptr}, FIND)->data,
+              reinterpret_cast<void *>(i));
+  }
+  hdestroy();
+}
+
+TEST(LlvmLibcHSearchTest, OnlyInsertWhenNotFound) {
+  using __llvm_libc::testing::ErrnoSetterMatcher::Fails;
+  ASSERT_GT(__llvm_libc::hcreate(16), 0);
+  for (size_t i = 0; i < 16 * 5; ++i) {
+    ASSERT_EQ(__llvm_libc::hsearch(
+                  {&search_data[i], reinterpret_cast<void *>(i)}, ENTER)
+                  ->key,
+              &search_data[i]);
+  }
+  for (size_t i = 0; i < 16 * 7; ++i) {
+    ASSERT_EQ(__llvm_libc::hsearch(
+                  {&search_data[i], reinterpret_cast<void *>(1000 + i)}, ENTER)
+                  ->key,
+              &search_data[i]);
+  }
+  for (size_t i = 0; i < 16 * 5; ++i) {
+    ASSERT_EQ(__llvm_libc::hsearch({&search_data[i], nullptr}, FIND)->data,
+              reinterpret_cast<void *>(i));
+  }
+  for (size_t i = 16 * 5; i < 16 * 7; ++i) {
+    ASSERT_EQ(__llvm_libc::hsearch({&search_data[i], nullptr}, FIND)->data,
+              reinterpret_cast<void *>(1000 + i));
+  }
+  hdestroy();
+}