diff --git a/clang/lib/AST/ByteCode/Context.cpp b/clang/lib/AST/ByteCode/Context.cpp
index 12bf3a3954b1b..74ec986e49ca7 100644
--- a/clang/lib/AST/ByteCode/Context.cpp
+++ b/clang/lib/AST/ByteCode/Context.cpp
@@ -21,7 +21,6 @@
 #include "clang/AST/ASTLambda.h"
 #include "clang/AST/Expr.h"
 #include "clang/Basic/TargetInfo.h"
-#include "llvm/Support/SystemZ/zOSSupport.h"
 
 using namespace clang;
 using namespace clang::interp;
diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
index c02c75f10b12f..908580f791f36 100644
--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -1294,6 +1294,11 @@ if(LLVM_TARGET_IS_CROSSCOMPILE_HOST)
 # (this is a variable that CrossCompile sets on recursive invocations)
 endif()
 
+# Special hack for z/OS for missing POSIX functions
+if (CMAKE_SYSTEM_NAME MATCHES "OS390")
+  include_directories(SYSTEM "${LLVM_MAIN_INCLUDE_DIR}/llvm/Support/SystemZ/zos_wrappers" )
+endif()
+
 if( "${CMAKE_SYSTEM_NAME}" MATCHES SunOS )
    # special hack for Solaris to handle crazy system sys/regset.h
    include_directories("${LLVM_MAIN_INCLUDE_DIR}/llvm/Support/Solaris")
diff --git a/llvm/include/llvm/Support/SystemZ/zOSSupport.h b/llvm/include/llvm/Support/SystemZ/zOSSupport.h
deleted file mode 100644
index f9a61f887d5dd..0000000000000
--- a/llvm/include/llvm/Support/SystemZ/zOSSupport.h
+++ /dev/null
@@ -1,47 +0,0 @@
-//===- zOSSupport.h - Common z/OS Include File ------------------*- 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
-//
-//===----------------------------------------------------------------------===//
-//
-// This file defines z/OS implementations for common functions.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_SUPPORT_ZOSSUPPORT_H
-#define LLVM_SUPPORT_ZOSSUPPORT_H
-
-#ifdef __MVS__
-#include <sys/resource.h>
-#include <sys/wait.h>
-
-// z/OS Unix System Services does not have strsignal() support, so the
-// strsignal() function is implemented here.
-inline char *strsignal(int sig) {
-  static char msg[256];
-  sprintf(msg, "%d", sig);
-  return msg;
-}
-
-// z/OS Unix System Services does not have wait4() support, so the wait4
-// function is implemented here.
-inline pid_t wait4(pid_t pid, int *wstatus, int options,
-                   struct rusage *rusage) {
-  pid_t Result = waitpid(pid, wstatus, options);
-  int GetrusageRC = getrusage(RUSAGE_CHILDREN, rusage);
-  assert(!GetrusageRC && "Must have valid measure of the resources!");
-  return Result;
-}
-
-// z/OS Unix System Services does not have strnlen() support, so the strnlen()
-// function is implemented here.
-inline std::size_t strnlen(const char *S, std::size_t MaxLen) {
-  const char *PtrToNullChar =
-      static_cast<const char *>(std::memchr(S, '\0', MaxLen));
-  return PtrToNullChar ? PtrToNullChar - S : MaxLen;
-}
-
-#endif
-#endif
diff --git a/llvm/include/llvm/Support/SystemZ/zos_wrappers/string.h b/llvm/include/llvm/Support/SystemZ/zos_wrappers/string.h
new file mode 100644
index 0000000000000..865eb8800397f
--- /dev/null
+++ b/llvm/include/llvm/Support/SystemZ/zos_wrappers/string.h
@@ -0,0 +1,35 @@
+//===- string.h - Common z/OS Include File ----------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares z/OS implementations for common functions.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_ZOSWRAPPERS_STRING_H
+#define LLVM_SUPPORT_ZOSWRAPPERS_STRING_H
+
+#include_next <string.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// z/OS Unix System Services does not have support for:
+// - strsignal()
+// - strnlen()
+// Implementations are provided for z/OS.
+
+char *strsignal(int sig) asm("llvm_zos_strsignal");
+
+size_t strnlen(const char *S, size_t MaxLen) asm("llvm_zos_strnlen");
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/llvm/lib/ObjCopy/MachO/MachOLayoutBuilder.cpp b/llvm/lib/ObjCopy/MachO/MachOLayoutBuilder.cpp
index 93bc6631e64c8..8660c903c617d 100644
--- a/llvm/lib/ObjCopy/MachO/MachOLayoutBuilder.cpp
+++ b/llvm/lib/ObjCopy/MachO/MachOLayoutBuilder.cpp
@@ -10,7 +10,6 @@
 #include "llvm/Support/Alignment.h"
 #include "llvm/Support/Errc.h"
 #include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/SystemZ/zOSSupport.h"
 
 using namespace llvm;
 using namespace llvm::objcopy::macho;
diff --git a/llvm/lib/ObjCopy/MachO/MachOObject.cpp b/llvm/lib/ObjCopy/MachO/MachOObject.cpp
index e45cc547ee446..e5f36c538ff7d 100644
--- a/llvm/lib/ObjCopy/MachO/MachOObject.cpp
+++ b/llvm/lib/ObjCopy/MachO/MachOObject.cpp
@@ -8,7 +8,6 @@
 
 #include "MachOObject.h"
 #include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/Support/SystemZ/zOSSupport.h"
 
 using namespace llvm;
 using namespace llvm::objcopy::macho;
diff --git a/llvm/lib/ObjCopy/MachO/MachOReader.cpp b/llvm/lib/ObjCopy/MachO/MachOReader.cpp
index 2b344f36d8e78..dd4d60deccbb8 100644
--- a/llvm/lib/ObjCopy/MachO/MachOReader.cpp
+++ b/llvm/lib/ObjCopy/MachO/MachOReader.cpp
@@ -10,7 +10,6 @@
 #include "MachOObject.h"
 #include "llvm/BinaryFormat/MachO.h"
 #include "llvm/Object/MachO.h"
-#include "llvm/Support/SystemZ/zOSSupport.h"
 #include <memory>
 
 using namespace llvm;
diff --git a/llvm/lib/ObjectYAML/MachOEmitter.cpp b/llvm/lib/ObjectYAML/MachOEmitter.cpp
index 46c91811d0a67..a4d17dfe1e320 100644
--- a/llvm/lib/ObjectYAML/MachOEmitter.cpp
+++ b/llvm/lib/ObjectYAML/MachOEmitter.cpp
@@ -19,7 +19,6 @@
 #include "llvm/Support/Error.h"
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/LEB128.h"
-#include "llvm/Support/SystemZ/zOSSupport.h"
 #include "llvm/Support/WithColor.h"
 #include "llvm/Support/YAMLTraits.h"
 #include "llvm/Support/raw_ostream.h"
diff --git a/llvm/lib/ObjectYAML/MachOYAML.cpp b/llvm/lib/ObjectYAML/MachOYAML.cpp
index 133358d395928..32015ddeb3618 100644
--- a/llvm/lib/ObjectYAML/MachOYAML.cpp
+++ b/llvm/lib/ObjectYAML/MachOYAML.cpp
@@ -15,7 +15,6 @@
 #include "llvm/BinaryFormat/MachO.h"
 #include "llvm/Support/YAMLTraits.h"
 #include "llvm/Support/raw_ostream.h"
-#include "llvm/Support/SystemZ/zOSSupport.h"
 #include "llvm/TargetParser/Host.h"
 #include <cstdint>
 #include <cstring>
diff --git a/llvm/lib/Support/CMakeLists.txt b/llvm/lib/Support/CMakeLists.txt
index 671a5fe941cef..a0980bda2a212 100644
--- a/llvm/lib/Support/CMakeLists.txt
+++ b/llvm/lib/Support/CMakeLists.txt
@@ -311,6 +311,7 @@ add_llvm_component_library(LLVMSupport
   Threading.cpp
   Valgrind.cpp
   Watchdog.cpp
+  zOSLibFunctions.cpp
 
   ADDITIONAL_HEADER_DIRS
   Unix
diff --git a/llvm/lib/Support/Unix/Program.inc b/llvm/lib/Support/Unix/Program.inc
index 4f17b2257a756..489ca03b30670 100644
--- a/llvm/lib/Support/Unix/Program.inc
+++ b/llvm/lib/Support/Unix/Program.inc
@@ -26,12 +26,11 @@
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/StringSaver.h"
-#include "llvm/Support/SystemZ/zOSSupport.h"
 #include "llvm/Support/raw_ostream.h"
-#include <sys/stat.h>
-#include <sys/resource.h>
-#include <signal.h>
 #include <fcntl.h>
+#include <signal.h>
+#include <sys/resource.h>
+#include <sys/stat.h>
 #if HAVE_UNISTD_H
 #include <unistd.h>
 #endif
diff --git a/llvm/lib/Support/zOSLibFunctions.cpp b/llvm/lib/Support/zOSLibFunctions.cpp
new file mode 100644
index 0000000000000..755b44fecba86
--- /dev/null
+++ b/llvm/lib/Support/zOSLibFunctions.cpp
@@ -0,0 +1,82 @@
+//===-- zOSLibFunctions.cpp -----------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+//===----------------------------------------------------------------------===//
+//
+// This file defines z/OS implementations for common functions.
+//
+//===----------------------------------------------------------------------===//
+
+#ifdef __MVS__
+#include <stdio.h>
+#include <string.h>
+#include <sys/resource.h>
+#include <sys/wait.h>
+
+const char *signalName[] = {
+    /*  0 */ nullptr,
+    /*  1 */ "Hangup",                   // SIGHUP
+    /*  2 */ "Interrupt",                // SIGINT
+    /*  3 */ "Aborted",                  // SIGABRT
+    /*  4 */ "Illegal instruction",      // SIGILL
+    /*  5 */ "Polling event",            // SIGPOLL
+    /*  6 */ "Socket data available",    // SIGURG
+    /*  7 */ "Stopped (signal)",         // SIGSTOP
+    /*  8 */ "Floating point exception", // SIGFPE
+    /*  9 */ "Killed",                   // SIGKILL
+    /* 10 */ "Bus error",                // SIGBUS
+    /* 11 */ "Segmentation fault",       // SIGSEGV
+    /* 12 */ "Bad system call",          // SIGSYS
+    /* 13 */ "Broken pipe",              // SIGPIPE
+    /* 14 */ "Alarm clock",              // SIGALRM
+    /* 15 */ "Terminated",               // SIGTERM
+    /* 16 */ "User defined signal 1",    // SIGUSR1
+    /* 17 */ "User defined signal 2",    // SIGUSR2
+    /* 18 */ "Abend",                    // SIGABND
+    /* 19 */ "Continued",                // SIGCONT
+    /* 20 */ "Child exited",             // SIGCHLD
+    /* 21 */ "Stopped (tty input)",      // SIGTTIN
+    /* 22 */ "Stopped (tty output)",     // SIGTTOU
+    /* 23 */ "I/O complete",             // SIGIO
+    /* 24 */ "Quit",                     // SIGQUIT
+    /* 25 */ "Stopped",                  // SIGTSTP
+    /* 26 */ "Trace/breakpoint trap",    // SIGTRAP
+    /* 27 */ "I/O error",                // SIGIOERR
+    /* 28 */ "Window changed",           // SIGWINCH
+    /* 29 */ "CPU time limit exceeded",  // SIGXCPU
+    /* 30 */ "File size limit exceeded", // SIGXFSZ
+    /* 31 */ "Virtual timer expired",    // SIGVTALRM
+    /* 32 */ "Profiling timer expired",  // SIGPROF
+    /* 33 */ "OMVS subsystem shutdown",  // SIGDANGER
+    /* 34 */ "Thread stop",              // SIGTHSTOP
+    /* 35 */ "Thread resume",            // SIGTHCONT
+    /* 36 */ nullptr,                    // n/a
+    /* 37 */ "Toggle syscall trace",     // SIGTRACE
+    /* 38 */ nullptr,                    // SIGDCE
+    /* 39 */ "System dump",              // SIGDUMP
+};
+
+// z/OS Unix System Services does not have strsignal() support, so the
+// strsignal() function is implemented here.
+char *strsignal(int sig) {
+  if (static_cast<size_t>(sig) < (sizeof(signalName) / sizeof(signalName[0])) &&
+      signalName[sig])
+    return const_cast<char *>(signalName[sig]);
+  static char msg[256];
+  sprintf(msg, "Unknown signal %d", sig);
+  return msg;
+}
+
+// z/OS Unix System Services does not have strnlen() support, so the strnlen()
+// function is implemented here.
+size_t strnlen(const char *S, size_t MaxLen) {
+  const char *PtrToNullChar =
+      static_cast<const char *>(memchr(S, '\0', MaxLen));
+  return PtrToNullChar ? PtrToNullChar - S : MaxLen;
+}
+#endif
diff --git a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
index 12fad7d57444f..a86be13f24882 100644
--- a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
+++ b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
@@ -27,7 +27,6 @@
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Program.h"
 #include "llvm/Support/Signals.h"
-#include "llvm/Support/SystemZ/zOSSupport.h"
 #include <cmath>
 #include <memory>
 #include <string>
diff --git a/llvm/tools/llvm-exegesis/lib/Error.cpp b/llvm/tools/llvm-exegesis/lib/Error.cpp
index 2908df25ddb1a..9024ba5ceb524 100644
--- a/llvm/tools/llvm-exegesis/lib/Error.cpp
+++ b/llvm/tools/llvm-exegesis/lib/Error.cpp
@@ -10,7 +10,6 @@
 #include "llvm/Config/llvm-config.h" // for LLVM_ON_UNIX
 
 #ifdef LLVM_ON_UNIX
-#include "llvm/Support/SystemZ/zOSSupport.h"
 #include <string.h>
 #endif // LLVM_ON_UNIX
 
diff --git a/llvm/tools/llvm-readobj/ELFDumper.cpp b/llvm/tools/llvm-readobj/ELFDumper.cpp
index 6f09da5a4099f..2b5bc631afd8d 100644
--- a/llvm/tools/llvm-readobj/ELFDumper.cpp
+++ b/llvm/tools/llvm-readobj/ELFDumper.cpp
@@ -61,7 +61,6 @@
 #include "llvm/Support/RISCVAttributeParser.h"
 #include "llvm/Support/RISCVAttributes.h"
 #include "llvm/Support/ScopedPrinter.h"
-#include "llvm/Support/SystemZ/zOSSupport.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <array>
diff --git a/llvm/tools/llvm-readobj/ObjDumper.cpp b/llvm/tools/llvm-readobj/ObjDumper.cpp
index 20e027aa5a5ef..1d193573b4776 100644
--- a/llvm/tools/llvm-readobj/ObjDumper.cpp
+++ b/llvm/tools/llvm-readobj/ObjDumper.cpp
@@ -21,7 +21,6 @@
 #include "llvm/Support/Error.h"
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/ScopedPrinter.h"
-#include "llvm/Support/SystemZ/zOSSupport.h"
 #include "llvm/Support/raw_ostream.h"
 #include <map>
 
diff --git a/llvm/tools/obj2yaml/macho2yaml.cpp b/llvm/tools/obj2yaml/macho2yaml.cpp
index 00220123e8189..f78ec8f3c265a 100644
--- a/llvm/tools/obj2yaml/macho2yaml.cpp
+++ b/llvm/tools/obj2yaml/macho2yaml.cpp
@@ -15,7 +15,6 @@
 #include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/LEB128.h"
-#include "llvm/Support/SystemZ/zOSSupport.h"
 
 #include <string.h> // for memcpy