diff --git a/libc/src/__support/CMakeLists.txt b/libc/src/__support/CMakeLists.txt
--- a/libc/src/__support/CMakeLists.txt
+++ b/libc/src/__support/CMakeLists.txt
@@ -54,3 +54,4 @@
 )
 
 add_subdirectory(FPUtil)
+add_subdirectory(OSUtil)
diff --git a/libc/src/__support/OSUtil/CMakeLists.txt b/libc/src/__support/OSUtil/CMakeLists.txt
new file mode 100644
--- /dev/null
+++ b/libc/src/__support/OSUtil/CMakeLists.txt
@@ -0,0 +1,10 @@
+add_subdirectory(linux)
+
+add_header_library(
+  osutil
+  HDRS
+    io.h
+    quick_exit.h
+  DEPENDS
+    libc.src.__support.OSUtil.linux.linux_util
+)
diff --git a/libc/src/__support/OSUtil/io.h b/libc/src/__support/OSUtil/io.h
new file mode 100644
--- /dev/null
+++ b/libc/src/__support/OSUtil/io.h
@@ -0,0 +1,16 @@
+//===---------------- Implementation of IO utils ----------------*- 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_OSUTIL_IO_H
+#define LLVM_LIBC_SRC_SUPPORT_OSUTIL_IO_H
+
+#ifdef __unix__
+#include "linux/io.h"
+#endif
+
+#endif // LLVM_LIBC_SRC_SUPPORT_OSUTIL_IO_H
diff --git a/libc/src/__support/OSUtil/linux/CMakeLists.txt b/libc/src/__support/OSUtil/linux/CMakeLists.txt
new file mode 100644
--- /dev/null
+++ b/libc/src/__support/OSUtil/linux/CMakeLists.txt
@@ -0,0 +1,10 @@
+add_header_library(
+  linux_util
+  HDRS
+    io.h
+    quick_exit.h
+  DEPENDS
+    libc.config.linux.linux_syscall_h
+    libc.include.sys_syscall
+    libc.src.string.string_utils
+)
diff --git a/libc/src/__support/OSUtil/linux/io.h b/libc/src/__support/OSUtil/linux/io.h
new file mode 100644
--- /dev/null
+++ b/libc/src/__support/OSUtil/linux/io.h
@@ -0,0 +1,25 @@
+//===-------------- Linux implementation of IO utils ------------*- 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_OSUTIL_LINUX_IO_H
+#define LLVM_LIBC_SRC_SUPPORT_OSUTIL_LINUX_IO_H
+
+#include "config/linux/syscall.h" // For internal syscall function.
+#include "include/sys/syscall.h"  // For syscall numbers.
+#include "src/string/string_utils.h"
+
+namespace __llvm_libc {
+
+static inline void write_to_stderr(const char *msg) {
+  __llvm_libc::syscall(SYS_write, 2 /* stderr */, msg,
+                       internal::string_length(msg));
+}
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_SUPPORT_OSUTIL_LINUX_IO_H
diff --git a/libc/src/__support/OSUtil/linux/quick_exit.h b/libc/src/__support/OSUtil/linux/quick_exit.h
new file mode 100644
--- /dev/null
+++ b/libc/src/__support/OSUtil/linux/quick_exit.h
@@ -0,0 +1,26 @@
+//===---------- Linux implementation of a quick exit function ---*- 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_OSUTIL_LINUX_QUICK_EXIT_H
+#define LLVM_LIBC_SRC_SUPPORT_OSUTIL_LINUX_QUICK_EXIT_H
+
+#include "config/linux/syscall.h" // For internal syscall function.
+#include "include/sys/syscall.h"  // For syscall numbers.
+
+namespace __llvm_libc {
+
+static inline void quick_exit(int status) {
+  for (;;) {
+    __llvm_libc::syscall(SYS_exit_group, status);
+    __llvm_libc::syscall(SYS_exit, status);
+  }
+}
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_SUPPORT_OSUTIL_LINUX_QUICK_EXIT_H
diff --git a/libc/src/__support/OSUtil/quick_exit.h b/libc/src/__support/OSUtil/quick_exit.h
new file mode 100644
--- /dev/null
+++ b/libc/src/__support/OSUtil/quick_exit.h
@@ -0,0 +1,16 @@
+//===---------- Implementation of a quick exit function ---------*- 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_OSUTIL_QUICK_EXIT_H
+#define LLVM_LIBC_SRC_SUPPORT_OSUTIL_QUICK_EXIT_H
+
+#ifdef __unix__
+#include "linux/quick_exit.h"
+#endif
+
+#endif // LLVM_LIBC_SRC_SUPPORT_OSUTIL_QUICK_EXIT_H
diff --git a/libc/test/loader/linux/CMakeLists.txt b/libc/test/loader/linux/CMakeLists.txt
--- a/libc/test/loader/linux/CMakeLists.txt
+++ b/libc/test/loader/linux/CMakeLists.txt
@@ -3,16 +3,21 @@
   return()
 endif()
 
+add_header_library(
+  loader_test
+  HDRS
+    loader_test.h
+  DEPENDS
+    libc.src.__support.OSUtil.osutil
+)
+
 add_loader_test(
   loader_args_test
   SRC
     args_test.cpp
   DEPENDS
+    .loader_test
     libc.loader.linux.crt1
-    libc.src.assert.__assert_fail
-    libc.src.signal.raise
-    libc.src.stdlib._Exit
-    libc.src.stdlib.abort
   ARGS
     1 2 3
   ENV
@@ -25,6 +30,7 @@
   SRC
     main_without_envp.cpp
   DEPENDS
+    .loader_test
     libc.loader.linux.crt1
 )
 
@@ -33,6 +39,7 @@
   SRC
     main_without_args.cpp
   DEPENDS
+    .loader_test
     libc.loader.linux.crt1
 )
 
diff --git a/libc/test/loader/linux/args_test.cpp b/libc/test/loader/linux/args_test.cpp
--- a/libc/test/loader/linux/args_test.cpp
+++ b/libc/test/loader/linux/args_test.cpp
@@ -6,8 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#undef NDEBUG
-#include "src/assert/assert.h"
+#include "loader_test.h"
 
 static bool my_streq(const char *lhs, const char *rhs) {
   const char *l, *r;
@@ -19,10 +18,10 @@
 }
 
 int main(int argc, char **argv, char **envp) {
-  assert(argc == 4 && "Unexpected argc.");
-  assert(my_streq(argv[1], "1") && "Unexpected argv[1].");
-  assert(my_streq(argv[2], "2") && "Unexpected argv[2].");
-  assert(my_streq(argv[3], "3") && "Unexpected argv[3].");
+  ASSERT_TRUE(argc == 4);
+  ASSERT_TRUE(my_streq(argv[1], "1"));
+  ASSERT_TRUE(my_streq(argv[2], "2"));
+  ASSERT_TRUE(my_streq(argv[3], "3"));
 
   bool found_france = false;
   bool found_germany = false;
@@ -33,8 +32,7 @@
       found_germany = true;
   }
 
-  assert(found_france && found_germany &&
-         "Did not find whats expected in envp.");
+  ASSERT_TRUE(found_france && found_germany);
 
   return 0;
 }
diff --git a/libc/test/loader/linux/loader_test.h b/libc/test/loader/linux/loader_test.h
new file mode 100644
--- /dev/null
+++ b/libc/test/loader/linux/loader_test.h
@@ -0,0 +1,27 @@
+//===-- Simple checkers for loader tests ------------------------*- 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_TEST_LOADER_LINUX_LOADER_TEST_H
+#define LLVM_LIBC_TEST_LOADER_LINUX_LOADER_TEST_H
+
+#include "src/__support/OSUtil/io.h"
+#include "src/__support/OSUtil/quick_exit.h"
+
+#define __AS_STRING(val) #val
+#define __CHECK(file, line, val, should_exit)                                  \
+  if (!(val)) {                                                                \
+    __llvm_libc::write_to_stderr(file ":" __AS_STRING(                         \
+        line) ": Expected '" #val "' to be true, but is false\n");             \
+    if (should_exit)                                                           \
+      __llvm_libc::quick_exit(127);                                            \
+  }
+
+#define EXPECT_TRUE(val) __CHECK(__FILE__, __LINE__, val, false)
+#define ASSERT_TRUE(val) __CHECK(__FILE__, __LINE__, val, true)
+
+#endif // LLVM_LIBC_TEST_LOADER_LINUX_LOADER_TEST_H