diff --git a/libc/src/stdfix/sqrtur.h b/libc/src/stdfix/sqrtur.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for sqrtur ------------------------*- 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_STDFIX_SQRTUR_H
+#define LLVM_LIBC_SRC_STDFIX_SQRTUR_H
+
+#include "include/llvm-libc-macros/stdfix-macros.h"
+
+namespace LIBC_NAMESPACE {
+
+unsigned fract sqrtur(unsigned fract x);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDFIX_SQRTUR_H
diff --git a/libc/test/src/stdfix/CMakeLists.txt b/libc/test/src/stdfix/CMakeLists.txt
@@ -22,6 +22,28 @@ foreach(suffix IN ITEMS hr r lr hk k lk)
   )
 endforeach()
 
+foreach(suffix IN ITEMS uhr ur ulr uhk uk)
+  add_libc_test(
+    sqrt${suffix}_test
+    SUITE
+      libc-stdfix-tests
+    HDRS
+      SqrtTest.h
+    SRCS
+      sqrt${suffix}_test.cpp
+    COMPILE_OPTIONS
+      -O3
+      -ffixed-point
+    DEPENDS
+      libc.src.stdfix.sqrt${suffix}
+      libc.src.__support.CPP.bit
+      libc.src.__support.fixed_point.fx_rep
+      libc.src.__support.fixed_point.sqrt
+      libc.src.__support.FPUtil.basic_operations
+      libc.src.__support.FPUtil.sqrt
+  )
+endforeach()
+
 foreach(suffix IN ITEMS hr r lr hk k lk uhr ur ulr uhk uk ulk)
   add_libc_test(
     round${suffix}_test

diff --git a/libc/test/src/stdfix/SqrtTest.h b/libc/test/src/stdfix/SqrtTest.h
@@ -0,0 +1,66 @@
+//===-- Utility class to test fixed-point sqrt ------------------*- 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 "test/UnitTest/Test.h"
+
+#include "src/__support/CPP/bit.h"
+#include "src/__support/FPUtil/BasicOperations.h"
+#include "src/__support/FPUtil/sqrt.h"
+#include "src/__support/fixed_point/fx_rep.h"
+#include "src/__support/fixed_point/sqrt.h"
+
+template <typename T> class SqrtTest : public LIBC_NAMESPACE::testing::Test {
+
+  using FXRep = LIBC_NAMESPACE::fixed_point::FXRep<T>;
+  static constexpr T zero = FXRep::ZERO();
+  static constexpr T min = FXRep::MIN();
+  static constexpr T max = FXRep::MAX();
+  static constexpr T half = static_cast<T>(0.5);
+  static constexpr T quarter = static_cast<T>(0.25);
+  static constexpr T one =
+      (FXRep::INTEGRAL_LEN > 0) ? static_cast<T>(1) : FXRep::MAX();
+  static constexpr T eps = FXRep::EPS();
+
+public:
+  typedef T (*SqrtFunc)(T);
+
+  void testSpecialNumbers(SqrtFunc func) {
+    EXPECT_EQ(zero, func(zero));
+    EXPECT_EQ(half, func(quarter));
+
+    if constexpr (FXRep::INTEGRAL_LEN) {
+      EXPECT_EQ(one, func(one));
+      EXPECT_EQ(static_cast<T>(2.0), func(static_cast<T>(4.0)));
+    }
+
+    using StorageType = typename FXRep::StorageType;
+
+    constexpr size_t COUNT = 255;
+    constexpr StorageType STEP =
+        ~StorageType(0) / static_cast<StorageType>(COUNT);
+    constexpr double ERR = 3.0 * static_cast<double>(eps);
+    StorageType x = 0;
+    for (size_t i = 0; i < COUNT; ++i, x += STEP) {
+      T v = LIBC_NAMESPACE::cpp::bit_cast<T>(x);
+      double v_d = static_cast<double>(v);
+      double errors = LIBC_NAMESPACE::fputil::abs(
+          static_cast<double>(func(v)) - LIBC_NAMESPACE::fputil::sqrt(v_d));
+      if (errors > ERR) {
+        // Print out the failure input and output.
+        EXPECT_EQ(v, zero);
+        EXPECT_EQ(func(v), zero);
+      }
+      ASSERT_TRUE(errors <= ERR);
+    }
+  }
+};
+
+#define LIST_SQRT_TESTS(T, func)                                               \
+  using LlvmLibcSqrtTest = SqrtTest<T>;                                        \
+  TEST_F(LlvmLibcSqrtTest, SpecialNumbers) { testSpecialNumbers(&func); }      \
+  static_assert(true, "Require semicolon.")
diff --git a/libc/test/src/stdfix/sqrtuhk_test.cpp b/libc/test/src/stdfix/sqrtuhk_test.cpp
@@ -0,0 +1,13 @@
+//===-- Unittests for sqrtuhk ---------------------------------------------===//
+//
+// 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 "SqrtTest.h"
+
+#include "src/stdfix/sqrtuhk.h"
+
+LIST_SQRT_TESTS(unsigned short accum, LIBC_NAMESPACE::sqrtuhk);
diff --git a/libc/test/src/stdfix/sqrtuhr_test.cpp b/libc/test/src/stdfix/sqrtuhr_test.cpp
@@ -0,0 +1,13 @@
+//===-- Unittests for sqrtuhr ---------------------------------------------===//
+//
+// 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 "SqrtTest.h"
+
+#include "src/stdfix/sqrtuhr.h"
+
+LIST_SQRT_TESTS(unsigned short fract, LIBC_NAMESPACE::sqrtuhr);
diff --git a/libc/test/src/stdfix/sqrtuk_test.cpp b/libc/test/src/stdfix/sqrtuk_test.cpp
@@ -0,0 +1,13 @@
+//===-- Unittests for sqrtuk ----------------------------------------------===//
+//
+// 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 "SqrtTest.h"
+
+#include "src/stdfix/sqrtuk.h"
+
+LIST_SQRT_TESTS(unsigned accum, LIBC_NAMESPACE::sqrtuk);
diff --git a/libc/test/src/stdfix/sqrtulr_test.cpp b/libc/test/src/stdfix/sqrtulr_test.cpp
@@ -0,0 +1,13 @@
+//===-- Unittests for sqrtulr ---------------------------------------------===//
+//
+// 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 "SqrtTest.h"
+
+#include "src/stdfix/sqrtulr.h"
+
+LIST_SQRT_TESTS(unsigned long fract, LIBC_NAMESPACE::sqrtulr);
diff --git a/libc/test/src/stdfix/sqrtur_test.cpp b/libc/test/src/stdfix/sqrtur_test.cpp
@@ -0,0 +1,13 @@
+//===-- Unittests for sqrtur ----------------------------------------------===//
+//
+// 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 "SqrtTest.h"
+
+#include "src/stdfix/sqrtur.h"
+
+LIST_SQRT_TESTS(unsigned fract, LIBC_NAMESPACE::sqrtur);