diff --git a/clang/lib/Basic/Targets/OSTargets.h b/clang/lib/Basic/Targets/OSTargets.h
--- a/clang/lib/Basic/Targets/OSTargets.h
+++ b/clang/lib/Basic/Targets/OSTargets.h
@@ -776,7 +776,9 @@
 
 public:
   ZOSTargetInfo(const llvm::Triple &Triple, const TargetOptions &Opts)
-      : OSTargetInfo<Target>(Triple, Opts) {}
+      : OSTargetInfo<Target>(Triple, Opts) {
+    this->WCharType = TargetInfo::UnsignedInt;
+  }
 };
 
 void addWindowsDefines(const llvm::Triple &Triple, const LangOptions &Opts,
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -3409,8 +3409,8 @@
     } else {
       bool IsARM = T.isARM() || T.isThumb() || T.isAArch64();
       CmdArgs.push_back("-fwchar-type=int");
-      if (IsARM && !(T.isOSWindows() || T.isOSNetBSD() ||
-                     T.isOSOpenBSD()))
+      if (T.isOSzOS() ||
+          (IsARM && !(T.isOSWindows() || T.isOSNetBSD() || T.isOSOpenBSD())))
         CmdArgs.push_back("-fno-signed-wchar");
       else
         CmdArgs.push_back("-fsigned-wchar");
diff --git a/clang/test/CodeGen/wchar-size.c b/clang/test/CodeGen/wchar-size.c
--- a/clang/test/CodeGen/wchar-size.c
+++ b/clang/test/CodeGen/wchar-size.c
@@ -1,6 +1,7 @@
 // RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm -o - %s | FileCheck %s -check-prefix=LONG-WCHAR
 // RUN: %clang_cc1 -triple x86_64-unknown-windows-msvc -emit-llvm -o - %s | FileCheck %s -check-prefix=SHORT-WCHAR
 // RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm -o - -fwchar-type=short -fno-signed-wchar %s | FileCheck %s -check-prefix=SHORT-WCHAR
+// RUN: %clang_cc1 -triple s390x-none-zos -emit-llvm -o - %s | FileCheck %s -check-prefix=LONG-WCHAR
 // Note: -fno-short-wchar implies the target default is used; so there is no
 // need to test this separately here.
 
diff --git a/clang/test/Lexer/wchar-signedness.c b/clang/test/Lexer/wchar-signedness.c
--- a/clang/test/Lexer/wchar-signedness.c
+++ b/clang/test/Lexer/wchar-signedness.c
@@ -1,9 +1,13 @@
 // RUN: %clang_cc1 -fsyntax-only -dM -E %s -triple x86_64-none-linux-gnu | FileCheck %s --check-prefix=CHECK-X86
 // RUN: %clang_cc1 -fsyntax-only -dM -E %s -triple armv7-none-eabi | FileCheck %s --check-prefix=CHECK-ARM
 // RUN: %clang_cc1 -fsyntax-only -dM -E %s -triple thumbv7-none-eabi | FileCheck %s --check-prefix=CHECK-ARM
+// RUN: %clang_cc1 -fsyntax-only -dM -E %s -triple s390x-none-zos | FileCheck %s --check-prefix=CHECK-ZOS
 
 // CHECK-X86-NOT: #define __WCHAR_UNSIGNED__
 // CHECK-X86: #define __WINT_UNSIGNED__ 1
 
 // CHECK-ARM: #define __WCHAR_UNSIGNED__ 1
 // CHECK-ARM-NOT: #define __WINT_UNSIGNED__ 1
+
+// CHECK-ZOS: #define __WCHAR_UNSIGNED__ 1
+// CHECK-ZOS-NOT: #define __WINT_UNSIGNED__ 1
diff --git a/clang/test/Preprocessor/wchar_t.c b/clang/test/Preprocessor/wchar_t.c
--- a/clang/test/Preprocessor/wchar_t.c
+++ b/clang/test/Preprocessor/wchar_t.c
@@ -48,6 +48,11 @@
 // CHECK-ARM64-AAPCS64-DAG: #define __WCHAR_TYPE__ unsigned int
 // CHECK-ARM64-AAPCS64-DAG: #define __WCHAR_UNSIGNED__ 1
 
+// RUN: %clang_cc1 -triple s390x-none-zos -fwchar-type=int -fno-signed-wchar -dM -E %s -o - | FileCheck %s -check-prefix CHECK-ZOS
+// CHECK-ZOS: #define __WCHAR_MAX__ 4294967295U
+// CHECK-ZOS: #define __WCHAR_TYPE__ unsigned int
+// CHECK-ZOS: #define __WCHAR_UNSIGNED__ 1
+
 // RUN: %clang_cc1 -triple xcore-unknown-unknown -fwchar-type=char -fno-signed-wchar -dM -E %s -o - | FileCheck %s -check-prefix CHECK-XCORE
 // CHECK-XCORE-DAG: #define __WCHAR_MAX__ 255
 // CHECK-XCORE-DAG: #define __WCHAR_TYPE__ unsigned char
diff --git a/clang/test/Sema/wchar.c b/clang/test/Sema/wchar.c
--- a/clang/test/Sema/wchar.c
+++ b/clang/test/Sema/wchar.c
@@ -6,7 +6,7 @@
 #if defined(_WIN32) || defined(_M_IX86) || defined(__CYGWIN__) \
  || defined(_M_X64) || defined(__ORBIS__) || defined(SHORT_WCHAR)
   #define WCHAR_T_TYPE unsigned short
-#elif defined(__arm) || defined(__aarch64__)
+#elif defined(__arm) || defined(__aarch64__) || defined(__MVS__)
   #define WCHAR_T_TYPE unsigned int
 #elif defined(__sun)
   #if defined(__LP64__)