diff --git a/libcxx/CMakeLists.txt b/libcxx/CMakeLists.txt
--- a/libcxx/CMakeLists.txt
+++ b/libcxx/CMakeLists.txt
@@ -465,8 +465,10 @@
 # These flags get added to CMAKE_CXX_FLAGS and CMAKE_C_FLAGS so that
 # 'config-ix' use them during feature checks. It also adds them to both
 # 'LIBCXX_COMPILE_FLAGS' and 'LIBCXX_LINK_FLAGS'
-if(ZOS)
-  add_target_flags_if_supported("-fzos-le-char-mode=ebcdic")
+if (LIBCXX_ASCII_ZOS_BUILD)
+  add_target_flags_if_supported("-DLIBCXX_BUILDING_LIBCXXABI")
+  add_target_flags_if_supported("-fzos-le-char-mode=ascii")
+  add_target_flags_if_supported("-I../${CMAKE_CXX_COMPILER_TARGET}/${LIBCXX_INSTALL_INCLUDE_DIR}")
 endif()
 
 if (${CMAKE_SYSTEM_NAME} MATCHES "AIX")
diff --git a/libcxx/cmake/caches/s390x-ibm-zos-ascii.cmake b/libcxx/cmake/caches/s390x-ibm-zos-ascii.cmake
new file mode 100644
--- /dev/null
+++ b/libcxx/cmake/caches/s390x-ibm-zos-ascii.cmake
@@ -0,0 +1,25 @@
+# Common
+set(CMAKE_BUILD_TYPE Release CACHE STRING "")
+
+set(LIBCXX_ENABLE_ABI_LINKER_SCRIPT OFF CACHE BOOL "")
+set(LIBCXX_ENABLE_SHARED ON CACHE BOOL "")
+set(LIBCXX_ENABLE_STATIC OFF CACHE BOOL "")
+set(LIBCXX_INCLUDE_TESTS OFF CACHE BOOL "")
+set(LIBCXX_INSTALL_HEADERS OFF CACHE BOOL "")
+set(LIBCXX_INCLUDE_BENCHMARKS OFF CACHE BOOL "")
+
+set(LIBCXXABI_ENABLE_SHARED OFF CACHE BOOL "")
+set(LIBCXXABI_ENABLE_STATIC OFF CACHE BOOL "")
+set(LIBCXXABI_INCLUDE_TESTS OFF CACHE BOOL "")
+
+set(LLVM_ENABLE_ASSERTIONS ON CACHE BOOL "")
+set(LLVM_ENABLE_WERROR ON CACHE BOOL "")
+
+# Target Specific
+set(LIBCXX_ASCII_ZOS_BUILD ON CACHE BOOL
+    "Build ascii version of libcxx library on z/OS.")
+set(LIBCXX_DLL_NAME CRTEQCXS CACHE STRING "")
+set(LIBCXX_SHARED_OUTPUT_NAME "c++_a" CACHE PATH
+    "Output name for the shared libc++ runtime library.")
+set(LIBCXX_EXCEPTION_ZOS_BUILD OFF CACHE BOOL
+    "Build libcxx exception library on z/OS as standalone.")
diff --git a/libcxx/cmake/caches/s390x-ibm-zos.cmake b/libcxx/cmake/caches/s390x-ibm-zos.cmake
new file mode 100644
--- /dev/null
+++ b/libcxx/cmake/caches/s390x-ibm-zos.cmake
@@ -0,0 +1,25 @@
+set(CMAKE_BUILD_TYPE Release CACHE STRING "")
+
+# Common
+set(LIBCXX_ENABLE_ABI_LINKER_SCRIPT OFF CACHE BOOL "")
+set(LIBCXX_ENABLE_SHARED ON CACHE BOOL "")
+set(LIBCXX_ENABLE_STATIC OFF CACHE BOOL "")
+set(LIBCXX_INCLUDE_TESTS ON CACHE BOOL "")
+
+set(LIBCXXABI_ENABLE_SHARED ON CACHE BOOL "")
+set(LIBCXXABI_ENABLE_STATIC OFF CACHE BOOL "")
+set(LIBCXXABI_INCLUDE_TESTS ON CACHE BOOL "")
+
+set(LLVM_ENABLE_ASSERTIONS ON CACHE BOOL "")
+set(LLVM_ENABLE_WERROR ON CACHE BOOL "")
+
+# Target Specific
+set(LIBCXX_DLL_NAME CRTEQCXE CACHE STRING "")
+set(LIBCXX_EXCEPTION_DLL_NAME CRTEQCXP CACHE STRING "")
+set(LIBCXX_EXCEPTION_ZOS_BUILD ON CACHE BOOL
+    "Build libcxx exception library on z/OS as standalone.")
+
+set(LIBCXXABI_DLL_NAME CRTEQCXA CACHE STRING "")
+set(LIBCXXABIXL_DLL_NAME CRTEQXLA CACHE STRING "")
+
+set(LLVM_EXTERNAL_UNWIND_SOURCE_DIR "$ENV{LLVM_BASE}/zos-unwind" CACHE PATH "The path to the external unwind source directory.")
diff --git a/libcxx/cmake/caches/s390x32-ibm-zos-ascii.cmake b/libcxx/cmake/caches/s390x32-ibm-zos-ascii.cmake
new file mode 100644
--- /dev/null
+++ b/libcxx/cmake/caches/s390x32-ibm-zos-ascii.cmake
@@ -0,0 +1,25 @@
+# Common
+set(CMAKE_BUILD_TYPE Release CACHE STRING "")
+
+set(LIBCXX_ENABLE_ABI_LINKER_SCRIPT OFF CACHE BOOL "")
+set(LIBCXX_ENABLE_SHARED ON CACHE BOOL "")
+set(LIBCXX_ENABLE_STATIC OFF CACHE BOOL "")
+set(LIBCXX_INCLUDE_TESTS OFF CACHE BOOL "")
+set(LIBCXX_INSTALL_HEADERS OFF CACHE BOOL "")
+set(LIBCXX_INCLUDE_BENCHMARKS OFF CACHE BOOL "")
+
+set(LIBCXXABI_ENABLE_SHARED OFF CACHE BOOL "")
+set(LIBCXXABI_ENABLE_STATIC OFF CACHE BOOL "")
+set(LIBCXXABI_INCLUDE_TESTS OFF CACHE BOOL "")
+
+set(LLVM_ENABLE_ASSERTIONS ON CACHE BOOL "")
+set(LLVM_ENABLE_WERROR ON CACHE BOOL "")
+
+# Target Specific
+set(LIBCXX_ASCII_ZOS_BUILD ON CACHE BOOL
+    "Build ascii version of libcxx library on z/OS.")
+set(LIBCXX_DLL_NAME CRTEHCXS CACHE STRING "")
+set(LIBCXX_SHARED_OUTPUT_NAME "c++_a" CACHE PATH
+    "Output name for the shared libc++ runtime library.")
+set(LIBCXX_EXCEPTION_ZOS_BUILD OFF CACHE BOOL
+    "Build libcxx exception library on z/OS as standalone.")
diff --git a/libcxx/cmake/caches/s390x32-ibm-zos.cmake b/libcxx/cmake/caches/s390x32-ibm-zos.cmake
new file mode 100644
--- /dev/null
+++ b/libcxx/cmake/caches/s390x32-ibm-zos.cmake
@@ -0,0 +1,26 @@
+# Common
+set(CMAKE_BUILD_TYPE Release CACHE STRING "")
+
+set(LIBCXX_ENABLE_ABI_LINKER_SCRIPT OFF CACHE BOOL "")
+set(LIBCXX_ENABLE_EXPERIMENTAL_LIBRARY OFF CACHE BOOL "")
+set(LIBCXX_ENABLE_SHARED ON CACHE BOOL "")
+set(LIBCXX_ENABLE_STATIC OFF CACHE BOOL "")
+set(LIBCXX_INCLUDE_TESTS ON CACHE BOOL "")
+
+set(LIBCXXABI_ENABLE_SHARED ON CACHE BOOL "")
+set(LIBCXXABI_ENABLE_STATIC OFF CACHE BOOL "")
+set(LIBCXXABI_INCLUDE_TESTS ON CACHE BOOL "")
+
+set(LLVM_ENABLE_ASSERTIONS ON CACHE BOOL "")
+set(LLVM_ENABLE_WERROR ON CACHE BOOL "")
+
+# Target Specific
+set(LIBCXX_DLL_NAME CRTEHCXE CACHE STRING "")
+set(LIBCXX_EXCEPTION_DLL_NAME CRTEHCXP CACHE STRING "")
+set(LIBCXX_EXCEPTION_ZOS_BUILD ON CACHE BOOL
+    "Build libcxx exception library on z/OS as standalone.")
+
+set(LIBCXXABI_DLL_NAME CRTEHCXA CACHE STRING "")
+set(LIBCXXABIXL_DLL_NAME CRTEHXLA CACHE STRING "")
+
+set(LLVM_EXTERNAL_UNWIND_SOURCE_DIR "$ENV{LLVM_BASE}/zos-unwind" CACHE PATH "The path to the external unwind source directory.")
diff --git a/libcxx/src/CMakeLists.txt b/libcxx/src/CMakeLists.txt
--- a/libcxx/src/CMakeLists.txt
+++ b/libcxx/src/CMakeLists.txt
@@ -196,10 +196,13 @@
 
 # Build the shared library.
 if (LIBCXX_ENABLE_SHARED)
+
   add_library(cxx_shared SHARED ${exclude_from_all} ${LIBCXX_SOURCES} ${LIBCXX_HEADERS})
   target_include_directories(cxx_shared PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
-  target_link_libraries(cxx_shared PUBLIC cxx-headers
-                                   PRIVATE ${LIBCXX_LIBRARIES})
+  if (NOT LIBCXX_ASCII_ZOS_BUILD)
+    target_link_libraries(cxx_shared PUBLIC cxx-headers
+                                     PRIVATE ${LIBCXX_LIBRARIES})
+  endif()
   set_target_properties(cxx_shared
     PROPERTIES
       COMPILE_FLAGS "${LIBCXX_COMPILE_FLAGS}"
@@ -212,10 +215,24 @@
   cxx_add_common_build_flags(cxx_shared)
   cxx_set_common_defines(cxx_shared)
 
+  if(ZOS)
+    STRING(REGEX REPLACE "-ascii/lib$" "/lib" SIDEDECK_DIR ${CMAKE_LIBRARY_OUTPUT_DIRECTORY})
+    target_link_libraries(cxx_shared PRIVATE
+      "-Wl,${SIDEDECK_DIR}/libunwind.x,${SIDEDECK_DIR}/libc++abi.x")
+
+    add_custom_command(TARGET cxx_shared POST_BUILD
+      COMMAND
+        ${LIBCXX_SOURCE_DIR}/utils/zos_rename_dll_side_deck.sh
+        $<TARGET_LINKER_FILE_NAME:cxx_shared> $<TARGET_FILE_NAME:cxx_shared> "${LIBCXX_DLL_NAME}"
+      COMMENT "Rename dll name inside the side deck file"
+      WORKING_DIRECTORY $<TARGET_FILE_DIR:cxx_shared>
+    )
+  endif()
+
   # Link against libc++abi
   if (LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY)
     target_link_libraries(cxx_shared PRIVATE libcxx-abi-shared-objects)
-  else()
+  elseif(NOT ZOS)
     target_link_libraries(cxx_shared PUBLIC libcxx-abi-shared)
   endif()