diff --git a/libc/src/__support/CPP/CMakeLists.txt b/libc/src/__support/CPP/CMakeLists.txt
--- a/libc/src/__support/CPP/CMakeLists.txt
+++ b/libc/src/__support/CPP/CMakeLists.txt
@@ -9,3 +9,11 @@
     TypeTraits.h
     Limits.h
 )
+
+add_header_library(
+  cpp_with_malloc
+  HDRS
+    vector.h
+  DEPENDS
+    libc.include.stdlib
+)
diff --git a/libc/src/__support/CPP/vector.h b/libc/src/__support/CPP/vector.h
new file mode 100644
--- /dev/null
+++ b/libc/src/__support/CPP/vector.h
@@ -0,0 +1,128 @@
+//===-- A self contained equivalent of std::vector --------------*- 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_SUPPORT_CPP_VECTOR_H
+#define LLVM_LIBC_SRC_SUPPORT_CPP_VECTOR_H
+
+#include <limits.h>
+#include <stddef.h> // For size_t.
+
+#include <stdlib.h> // For malloc/realloc/free
+
+namespace __llvm_libc {
+namespace cpp {
+
+void simple_memset(void *dst, char value, size_t count) {
+  char *data_array = static_cast<char *>(dst);
+  for (size_t i = 0; i < count; ++i)
+    data_array[i] = value;
+}
+
+// This implementation does not have a templated allocator since that feature
+// isn't relevant for a libc setting.
+
+// Vector is a templated dynamically resizable array. This implementation is
+// only meant for primitives or structs, and will not call destructors on held
+// objects.
+template <class T> class vector {
+  T *data_array;
+  size_t array_size;
+  size_t num_elements = 0;
+  static constexpr size_t DEFAULT_SIZE = 16;
+  static constexpr size_t GROWTH_FACTOR = 2;
+  static constexpr size_t MAX_SIZE = __SIZE_MAX__;
+
+public:
+  constexpr vector<T>() : array_size{DEFAULT_SIZE} {
+    data_array = static_cast<T *>(malloc(DEFAULT_SIZE * sizeof(T)));
+  }
+  constexpr vector<T>(size_t count) : array_size{count} {
+    data_array = static_cast<T *>(malloc(count * sizeof(T)));
+  }
+  constexpr vector<T>(const vector<T> &other) {
+    array_size = other.capacity();
+    data_array = static_cast<T *>(malloc(array_size * sizeof(T)));
+    num_elements = other.size();
+    for (size_t i = 0; i < num_elements; ++i)
+      data_array[i] = other.data()[i];
+  }
+
+  ~vector() { free(data_array); }
+
+  constexpr vector &operator=(vector &other) {
+    if (this == &other)
+      return *this;
+
+    array_size = other.capacity();
+    data_array = static_cast<T *>(malloc(array_size * sizeof(T)));
+    num_elements = other.size();
+    for (size_t i = 0; i < num_elements; ++i)
+      data_array[i] = other.data()[i];
+    return *this;
+  }
+
+  // can only increase the size of the array
+  constexpr void reserve(size_t new_cap) {
+    if (new_cap < array_size || new_cap > MAX_SIZE)
+      return;
+    array_size = new_cap;
+    realloc_array();
+  }
+
+  constexpr void shrink_to_fit() {
+    array_size = num_elements;
+    realloc_array();
+  }
+
+  constexpr void push_back(const T &value) {
+    if (num_elements >= array_size)
+      increase_size(num_elements + 1);
+    data_array[num_elements] = value;
+    ++num_elements;
+  }
+
+  constexpr T &operator[](size_t pos) {
+    if (pos >= num_elements)
+      num_elements = pos + 1;
+    return data_array[pos];
+  }
+  constexpr T *data() { return data_array; }
+  constexpr const T *data() const { return data_array; }
+
+  constexpr bool empty() const { return num_elements == 0; }
+
+  constexpr size_t size() const { return num_elements; }
+  constexpr size_t max_size() const { return MAX_SIZE; }
+
+  constexpr size_t capacity() const { return array_size; }
+
+  // new_size is treated as the minimum size for the new array. This function
+  // will increase array_size by GROWTH_FACTOR until there is space for new_size
+  // items.
+  constexpr void increase_size(size_t new_size) {
+    size_t temp_size = array_size;
+    if (temp_size == 0)
+      ++temp_size;
+    while (temp_size < new_size)
+      temp_size = temp_size * GROWTH_FACTOR;
+    if (temp_size >= MAX_SIZE)
+      return;
+    array_size = temp_size;
+    realloc_array();
+  }
+
+private:
+  // calls realloc on data_array so that its size matches array_size
+  constexpr void realloc_array() {
+    data_array = static_cast<T *>(realloc(data_array, array_size * sizeof(T)));
+  }
+};
+} // namespace cpp
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_SUPPORT_CPP_VECTOR_H
diff --git a/libc/test/utils/CPP/CMakeLists.txt b/libc/test/utils/CPP/CMakeLists.txt
--- a/libc/test/utils/CPP/CMakeLists.txt
+++ b/libc/test/utils/CPP/CMakeLists.txt
@@ -39,3 +39,13 @@
   DEPENDS
     libc.src.__support.CPP.standalone_cpp
 )
+
+add_libc_unittest(
+  vector_test
+  SUITE
+    libc_cpp_utils_unittests
+  SRCS
+    vector_test.cpp
+  DEPENDS
+    libc.src.__support.CPP.cpp_with_malloc
+)
diff --git a/libc/test/utils/CPP/vector_test.cpp b/libc/test/utils/CPP/vector_test.cpp
new file mode 100644
--- /dev/null
+++ b/libc/test/utils/CPP/vector_test.cpp
@@ -0,0 +1,53 @@
+//===-- Unittests for vector ----------------------------------------------===//
+//
+// 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/__support/CPP/vector.h"
+#include "utils/UnitTest/Test.h"
+
+TEST(LlvmLibcVectorTest, SimpleConstructors) {
+  __llvm_libc::cpp::vector<int> vec;
+
+  __llvm_libc::cpp::vector<int> vec2 = __llvm_libc::cpp::vector<int>(10);
+
+  __llvm_libc::cpp::vector<int> vec3 = __llvm_libc::cpp::vector<int>(vec2);
+}
+
+TEST(LlvmLibcVectorTest, OrderedWriteOrderedReadTest) {
+  __llvm_libc::cpp::vector<size_t> vec;
+
+  for (size_t i = 0; i < 100; i = i + 2) {
+    vec.push_back(i);
+  }
+  ASSERT_EQ(vec.size(), size_t(50));
+  ASSERT_GE(vec.capacity(), vec.size());
+  for (size_t j = 0; j < vec.size(); ++j) {
+    ASSERT_EQ(vec[j], j * 2);
+  }
+}
+
+TEST(LlvmLibcVectorTest, RandomWriteOrderedReadTest) {
+  __llvm_libc::cpp::vector<bool> vec = __llvm_libc::cpp::vector<bool>(0);
+
+  ASSERT_EQ(vec.capacity(), size_t(0));
+
+  size_t index_array[] = {5, 2, 7, 4, 8, 9, 1, 3, 6, 0};
+  for (size_t i = 0; i < 10; ++i) {
+    if (vec.capacity() < index_array[i]) {
+      vec.increase_size(index_array[i]);
+      ASSERT_GE(vec.capacity(), index_array[i]);
+    }
+
+    vec[index_array[i]] = ((index_array[i] % 3) == 0);
+  }
+
+  ASSERT_GE(vec.capacity(), size_t(10));
+
+  for (size_t j = 0; j < 10; ++j) {
+    ASSERT_EQ(vec[j], (j % 3) == 0);
+  }
+}