diff --git a/libc/test/src/stdio/fscanf_test.cpp b/libc/test/src/stdio/fscanf_test.cpp
@@ -0,0 +1,73 @@
+//===-- Unittests for fscanf ----------------------------------------------===//
+//
+// 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/string_view.h"
+#include "src/stdio/fclose.h"
+#include "src/stdio/ferror.h"
+#include "src/stdio/fopen.h"
+#include "src/stdio/fwrite.h"
+
+#include "src/stdio/fscanf.h"
+
+#include "utils/UnitTest/Test.h"
+
+#include <errno.h>
+#include <stdio.h>
+
+TEST(LlvmLibcFScanfTest, WriteToFile) {
+  constexpr char FILENAME[] = "testdata/fscanf_output.test";
+  ::FILE *file = __llvm_libc::fopen(FILENAME, "w");
+  ASSERT_FALSE(file == nullptr);
+
+  int read;
+
+  constexpr char simple[] = "A simple string with no conversions.\n";
+
+  ASSERT_EQ(sizeof(simple) - 1,
+            __llvm_libc::fwrite(simple, 1, sizeof(simple) - 1, file));
+
+  constexpr char numbers[] = "1234567890\n";
+
+  ASSERT_EQ(sizeof(numbers) - 1,
+            __llvm_libc::fwrite(numbers, 1, sizeof(numbers) - 1, file));
+
+  constexpr char numbers_and_more[] = "1234 and more\n";
+
+  ASSERT_EQ(sizeof(numbers_and_more) - 1,
+            __llvm_libc::fwrite(numbers_and_more, 1,
+                                sizeof(numbers_and_more) - 1, file));
+
+  read =
+      __llvm_libc::fscanf(file, "Reading from a write-only file should fail.");
+  EXPECT_LT(read, 0);
+
+  ASSERT_EQ(0, __llvm_libc::fclose(file));
+
+  file = __llvm_libc::fopen(FILENAME, "r");
+  ASSERT_FALSE(file == nullptr);
+
+  char data[50];
+  read = __llvm_libc::fscanf(file, "%[A-Za-z .\n]", data);
+  ASSERT_EQ(read, 1);
+  ASSERT_STREQ(simple, data);
+
+  read = __llvm_libc::fscanf(file, "%s", data);
+  ASSERT_EQ(read, 1);
+  ASSERT_EQ(__llvm_libc::cpp::string_view(numbers, 10),
+            __llvm_libc::cpp::string_view(data));
+
+  // The format string starts with a space to handle the fact that the %s leaves
+  // a trailing \n and %c doesn't strip leading whitespace.
+  read = __llvm_libc::fscanf(file, " %50c", data);
+  ASSERT_EQ(read, 1);
+  ASSERT_EQ(__llvm_libc::cpp::string_view(numbers_and_more),
+            __llvm_libc::cpp::string_view(data, sizeof(numbers_and_more) - 1));
+
+  ASSERT_EQ(__llvm_libc::ferror(file), 0);
+  ASSERT_EQ(__llvm_libc::fclose(file), 0);
+}
diff --git a/libc/test/src/stdio/sscanf_test.cpp b/libc/test/src/stdio/sscanf_test.cpp
@@ -0,0 +1,30 @@
+//===-- Unittests for sscanf ----------------------------------------------===//
+//
+// 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/stdio/sscanf.h"
+
+#include "utils/UnitTest/Test.h"
+
+TEST(LlvmLibcSScanfTest, SimpleStringConv) {
+  int ret_val;
+  char buffer[10];
+  char buffer2[10];
+  ret_val = __llvm_libc::sscanf("abc123", "abc %s", buffer);
+  ASSERT_EQ(ret_val, 1);
+  ASSERT_STREQ(buffer, "123");
+
+  ret_val = __llvm_libc::sscanf("abc123", "%3s %3s", buffer, buffer2);
+  ASSERT_EQ(ret_val, 2);
+  ASSERT_STREQ(buffer, "abc");
+  ASSERT_STREQ(buffer2, "123");
+
+  ret_val = __llvm_libc::sscanf("abc 123", "%3s%3s", buffer, buffer2);
+  ASSERT_EQ(ret_val, 2);
+  ASSERT_STREQ(buffer, "abc");
+  ASSERT_STREQ(buffer2, "123");
+}