diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
index cfd1a086c0fc2..9884ad3579268 100644
--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -572,6 +572,10 @@ else()
   option(LLVM_ENABLE_THREADS "Use threads if available." ON)
 endif()
 
+set(LLVM_ENABLE_ICU "OFF" CACHE STRING "Use ICU for character conversion support if available. Can be ON, OFF, or FORCE_ON")
+
+set(LLVM_ENABLE_ICONV "OFF" CACHE STRING "Use iconv for character conversion support if available. Can be ON, OFF, or FORCE_ON")
+
 set(LLVM_ENABLE_ZLIB "ON" CACHE STRING "Use zlib for compression/decompression if available. Can be ON, OFF, or FORCE_ON")
 
 set(LLVM_ENABLE_ZSTD "ON" CACHE STRING "Use zstd for compression/decompression if available. Can be ON, OFF, or FORCE_ON")
diff --git a/llvm/cmake/config-ix.cmake b/llvm/cmake/config-ix.cmake
index 15ae04f5a6913..e8ccbf6f006b9 100644
--- a/llvm/cmake/config-ix.cmake
+++ b/llvm/cmake/config-ix.cmake
@@ -294,6 +294,41 @@ if(LLVM_HAS_LOGF128)
   set(LLVM_HAS_LOGF128 "${HAS_LOGF128}")
 endif()
 
+if (LLVM_ENABLE_ICU STREQUAL FORCE_ON AND LLVM_ENABLE_ICONV STREQUAL FORCE_ON)
+  message(FATAL_ERROR "LLVM_ENABLE_ICU and LLVM_ENABLE_ICONV should not both be FORCE_ON")
+endif()
+
+# Check for ICU. Only allow an optional, dynamic link for ICU so we don't impact LLVM's licensing.
+if(LLVM_ENABLE_ICU AND NOT(LLVM_ENABLE_ICONV STREQUAL FORCE_ON))
+  set(LIBRARY_SUFFIXES ${CMAKE_FIND_LIBRARY_SUFFIXES})
+  set(CMAKE_FIND_LIBRARY_SUFFIXES "${CMAKE_SHARED_LIBRARY_SUFFIX}")
+  if (LLVM_ENABLE_ICU STREQUAL FORCE_ON)
+    find_package(ICU REQUIRED COMPONENTS uc i18n)
+    if (NOT ICU_FOUND)
+      message(FATAL_ERROR "Failed to configure ICU, but LLVM_ENABLE_ICU is FORCE_ON")
+    endif()
+  else()
+    find_package(ICU COMPONENTS uc i18n)
+  endif()
+  set(HAVE_ICU ${ICU_FOUND})
+  set(CMAKE_FIND_LIBRARY_SUFFIXES ${LIBRARY_SUFFIXES})
+endif()
+
+# Check for builtin iconv to avoid licensing issues.
+if(LLVM_ENABLE_ICONV AND NOT HAVE_ICU)
+  if (LLVM_ENABLE_ICONV STREQUAL FORCE_ON)
+    find_package(Iconv REQUIRED)
+    if (NOT Iconv_FOUND OR NOT Iconv_IS_BUILT_IN)
+      message(FATAL_ERROR "Failed to configure iconv, but LLVM_ENABLE_ICONV is FORCE_ON")
+    endif()
+  else()
+    find_package(Iconv)
+  endif()
+  if(Iconv_FOUND AND Iconv_IS_BUILT_IN)
+    set(HAVE_ICONV 1)
+  endif()
+endif()
+
 # function checks
 check_symbol_exists(arc4random "stdlib.h" HAVE_DECL_ARC4RANDOM)
 find_package(Backtrace)
diff --git a/llvm/include/llvm/Config/config.h.cmake b/llvm/include/llvm/Config/config.h.cmake
index 835201f2a45b0..5ea40f73b15af 100644
--- a/llvm/include/llvm/Config/config.h.cmake
+++ b/llvm/include/llvm/Config/config.h.cmake
@@ -240,6 +240,12 @@
 /* Have host's ___chkstk_ms */
 #cmakedefine HAVE____CHKSTK_MS ${HAVE____CHKSTK_MS}
 
+/* Define if ICU library is available */
+#cmakedefine HAVE_ICU ${HAVE_ICU}
+
+/* Define if iconv library is available */
+#cmakedefine HAVE_ICONV ${HAVE_ICONV}
+
 /* Linker version detected at compile time. */
 #cmakedefine HOST_LINK_VERSION "${HOST_LINK_VERSION}"
 
diff --git a/llvm/include/llvm/Support/CharSet.h b/llvm/include/llvm/Support/CharSet.h
new file mode 100644
index 0000000000000..6a28cd19f4143
--- /dev/null
+++ b/llvm/include/llvm/Support/CharSet.h
@@ -0,0 +1,141 @@
+//===-- CharSet.h - Characters set conversion class ---------------*- 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file provides a utility class to convert between different character
+/// set encodings.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_CHARSET_H
+#define LLVM_SUPPORT_CHARSET_H
+
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Config/config.h"
+#include "llvm/Support/ErrorOr.h"
+
+#include <string>
+#include <system_error>
+
+namespace llvm {
+
+template <typename T> class SmallVectorImpl;
+
+namespace details {
+class CharSetConverterImplBase {
+
+private:
+  /// Converts a string.
+  /// \param[in] Source source string
+  /// \param[out] Result container for converted string
+  /// \return error code in case something went wrong
+  ///
+  /// The following error codes can occur, among others:
+  ///   - std::errc::argument_list_too_long: The result requires more than
+  ///     std::numeric_limits<size_t>::max() bytes.
+  ///   - std::errc::illegal_byte_sequence: The input contains an invalid
+  ///     multibyte sequence.
+  ///   - std::errc::invalid_argument: The input contains an incomplete
+  ///     multibyte sequence.
+  ///
+  /// If the destination charset is a stateful character set, the shift state
+  /// will be set to the initial state.
+  ///
+  /// In case of an error, the result string contains the successfully converted
+  /// part of the input string.
+  ///
+  virtual std::error_code convertString(StringRef Source,
+                                        SmallVectorImpl<char> &Result) = 0;
+
+  /// Resets the converter to the initial state.
+  virtual void reset() = 0;
+
+public:
+  virtual ~CharSetConverterImplBase() = default;
+
+  /// Converts a string and resets the converter to the initial state.
+  std::error_code convert(StringRef Source, SmallVectorImpl<char> &Result) {
+    auto EC = convertString(Source, Result);
+    reset();
+    return EC;
+  }
+};
+} // namespace details
+
+// Names inspired by https://wg21.link/p1885.
+namespace text_encoding {
+enum class id {
+  /// UTF-8 character set encoding.
+  UTF8,
+
+  /// IBM EBCDIC 1047 character set encoding.
+  IBM1047
+};
+} // end namespace text_encoding
+
+/// Utility class to convert between different character set encodings.
+class CharSetConverter {
+  std::unique_ptr<details::CharSetConverterImplBase> Converter;
+
+  CharSetConverter(std::unique_ptr<details::CharSetConverterImplBase> Converter)
+      : Converter(std::move(Converter)) {}
+
+public:
+  /// Creates a CharSetConverter instance.
+  /// Returns std::errc::invalid_argument in case the requested conversion is
+  /// not supported.
+  /// \param[in] CSFrom the source character encoding
+  /// \param[in] CSTo the target character encoding
+  /// \return a CharSetConverter instance or an error code
+  static ErrorOr<CharSetConverter> create(text_encoding::id CSFrom,
+                                          text_encoding::id CSTo);
+
+  /// Creates a CharSetConverter instance.
+  /// Returns std::errc::invalid_argument in case the requested conversion is
+  /// not supported.
+  /// \param[in] CPFrom name of the source character encoding
+  /// \param[in] CPTo name of the target character encoding
+  /// \return a CharSetConverter instance or an error code
+  static ErrorOr<CharSetConverter> create(StringRef CPFrom, StringRef CPTo);
+
+  CharSetConverter(const CharSetConverter &) = delete;
+  CharSetConverter &operator=(const CharSetConverter &) = delete;
+
+  CharSetConverter(CharSetConverter &&Other)
+      : Converter(std::move(Other.Converter)) {}
+
+  CharSetConverter &operator=(CharSetConverter &&Other) {
+    if (this != &Other)
+      Converter = std::move(Other.Converter);
+    return *this;
+  }
+
+  ~CharSetConverter() = default;
+
+  /// Converts a string.
+  /// \param[in] Source source string
+  /// \param[out] Result container for converted string
+  /// \return error code in case something went wrong
+  std::error_code convert(StringRef Source,
+                          SmallVectorImpl<char> &Result) const {
+    return Converter->convert(Source, Result);
+  }
+
+  ErrorOr<std::string> convert(StringRef Source) const {
+    SmallString<100> Result;
+    auto EC = Converter->convert(Source, Result);
+    if (!EC)
+      return std::string(Result);
+    return EC;
+  }
+};
+
+} // namespace llvm
+
+#endif
diff --git a/llvm/lib/Support/CMakeLists.txt b/llvm/lib/Support/CMakeLists.txt
index 98ffd829d80b8..d5d822784340b 100644
--- a/llvm/lib/Support/CMakeLists.txt
+++ b/llvm/lib/Support/CMakeLists.txt
@@ -162,6 +162,7 @@ add_llvm_component_library(LLVMSupport
   CachePruning.cpp
   Caching.cpp
   circular_raw_ostream.cpp
+  CharSet.cpp
   Chrono.cpp
   COM.cpp
   CodeGenCoverage.cpp
@@ -315,6 +316,14 @@ add_llvm_component_library(LLVMSupport
   Demangle
   )
 
+# Link ICU library if it is an external library.
+if(ICU_FOUND)
+  target_link_libraries(LLVMSupport
+  PRIVATE
+  ${ICU_LIBRARIES}
+  )
+endif()
+
 set(llvm_system_libs ${system_libs})
 
 # This block is only needed for llvm-config. When we deprecate llvm-config and
diff --git a/llvm/lib/Support/CharSet.cpp b/llvm/lib/Support/CharSet.cpp
new file mode 100644
index 0000000000000..6810cf9c6e376
--- /dev/null
+++ b/llvm/lib/Support/CharSet.cpp
@@ -0,0 +1,344 @@
+//===-- CharSet.cpp - Characters sets conversion class ------------*- 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file provides utility classes to convert between different character
+/// set encodings.
+///
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/CharSet.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Support/ConvertEBCDIC.h"
+#include "llvm/Support/raw_ostream.h"
+#include <algorithm>
+#include <limits>
+#include <system_error>
+
+#ifdef HAVE_ICU
+#include <unicode/ucnv.h>
+#elif defined(HAVE_ICONV)
+#include <iconv.h>
+#endif
+
+using namespace llvm;
+
+// Normalize the charset name with the charset alias matching algorithm proposed
+// in https://www.unicode.org/reports/tr22/tr22-8.html#Charset_Alias_Matching.
+static void normalizeCharSetName(StringRef CSName,
+                                 SmallVectorImpl<char> &Normalized) {
+  bool PrevDigit = false;
+  for (auto Ch : CSName) {
+    if (isAlnum(Ch)) {
+      Ch = toLower(Ch);
+      if (Ch != '0' || PrevDigit) {
+        PrevDigit = isDigit(Ch);
+        Normalized.push_back(Ch);
+      }
+    }
+  }
+}
+
+// Maps the charset name to enum constant if possible.
+static std::optional<text_encoding::id> getKnownCharSet(StringRef CSName) {
+  SmallString<16> Normalized;
+  normalizeCharSetName(CSName, Normalized);
+  if (Normalized.equals("utf8"))
+    return text_encoding::id::UTF8;
+  if (Normalized.equals("ibm1047"))
+    return text_encoding::id::IBM1047;
+  return std::nullopt;
+}
+
+LLVM_ATTRIBUTE_UNUSED static void
+HandleOverflow(size_t &Capacity, char *&Output, size_t &OutputLength,
+               SmallVectorImpl<char> &Result) {
+  // No space left in output buffer. Double the size of the underlying
+  // memory in the SmallVectorImpl, adjust pointer and length and continue
+  // the conversion.
+  Capacity = (Capacity < std::numeric_limits<size_t>::max() / 2)
+                 ? 2 * Capacity
+                 : std::numeric_limits<size_t>::max();
+  Result.resize(0);
+  Result.resize_for_overwrite(Capacity);
+  Output = static_cast<char *>(Result.data());
+  OutputLength = Capacity;
+}
+
+namespace {
+enum ConversionType {
+  UTF8ToIBM1047,
+  IBM1047ToUTF8,
+};
+
+// Support conversion between EBCDIC 1047 and UTF-8. This class uses
+// built-in translation tables that allow for translation between the
+// aforementioned character sets. The use of tables for conversion is only
+// possible because EBCDIC 1047 is a single-byte, stateless encoding; other
+// character sets are not supported.
+class CharSetConverterTable : public details::CharSetConverterImplBase {
+  const ConversionType ConvType;
+
+public:
+  CharSetConverterTable(ConversionType ConvType) : ConvType(ConvType) {}
+
+  std::error_code convertString(StringRef Source,
+                                SmallVectorImpl<char> &Result) override;
+
+  void reset() override {}
+};
+
+std::error_code
+CharSetConverterTable::convertString(StringRef Source,
+                                     SmallVectorImpl<char> &Result) {
+  if (ConvType == IBM1047ToUTF8) {
+    ConverterEBCDIC::convertToUTF8(Source, Result);
+    return std::error_code();
+  } else if (ConvType == UTF8ToIBM1047) {
+    return ConverterEBCDIC::convertToEBCDIC(Source, Result);
+  }
+  llvm_unreachable("Invalid ConvType!");
+  return std::error_code();
+}
+
+#ifdef HAVE_ICU
+struct UConverterDeleter {
+  void operator()(UConverter *Converter) const {
+    if (Converter)
+      ucnv_close(Converter);
+  }
+};
+using UConverterUniquePtr = std::unique_ptr<UConverter, UConverterDeleter>;
+
+class CharSetConverterICU : public details::CharSetConverterImplBase {
+  UConverterUniquePtr FromConvDesc;
+  UConverterUniquePtr ToConvDesc;
+
+public:
+  CharSetConverterICU(UConverterUniquePtr FromConverter,
+                      UConverterUniquePtr ToConverter)
+      : FromConvDesc(std::move(FromConverter)),
+        ToConvDesc(std::move(ToConverter)) {}
+
+  std::error_code convertString(StringRef Source,
+                                SmallVectorImpl<char> &Result) override;
+
+  void reset() override;
+};
+
+std::error_code
+CharSetConverterICU::convertString(StringRef Source,
+                                   SmallVectorImpl<char> &Result) {
+  // Setup the input in case it has no backing data.
+  size_t InputLength = Source.size();
+  const char *In = InputLength ? const_cast<char *>(Source.data()) : "";
+
+  // Setup the output. We directly write into the SmallVector.
+  size_t Capacity = Result.capacity();
+  size_t OutputLength = Capacity;
+  Result.resize_for_overwrite(Capacity);
+  char *Output = static_cast<char *>(Result.data());
+  UErrorCode EC = U_ZERO_ERROR;
+
+  ucnv_setToUCallBack(&*FromConvDesc, UCNV_TO_U_CALLBACK_STOP, NULL, NULL, NULL,
+                      &EC);
+  ucnv_setFromUCallBack(&*ToConvDesc, UCNV_FROM_U_CALLBACK_STOP, NULL, NULL,
+                        NULL, &EC);
+  assert(U_SUCCESS(EC));
+
+  do {
+    EC = U_ZERO_ERROR;
+    const char *Input = In;
+
+    Output = InputLength ? static_cast<char *>(Result.data()) : nullptr;
+    ucnv_convertEx(&*ToConvDesc, &*FromConvDesc, &Output, Result.end(), &Input,
+                   In + InputLength, /*pivotStart=*/NULL,
+                   /*pivotSource=*/NULL, /*pivotTarget=*/NULL,
+                   /*pivotLimit=*/NULL, /*reset=*/true,
+                   /*flush=*/true, &EC);
+    if (U_FAILURE(EC)) {
+      if (EC == U_BUFFER_OVERFLOW_ERROR &&
+          Capacity < std::numeric_limits<size_t>::max()) {
+        HandleOverflow(Capacity, Output, OutputLength, Result);
+        continue;
+      }
+      // Some other error occured.
+      Result.resize(Output - Result.data());
+      return std::error_code(EILSEQ, std::generic_category());
+    }
+    break;
+  } while (true);
+
+  Result.resize(Output - Result.data());
+  return std::error_code();
+}
+
+void CharSetConverterICU::reset() {
+  ucnv_reset(&*FromConvDesc);
+  ucnv_reset(&*ToConvDesc);
+}
+
+#elif defined(HAVE_ICONV)
+class CharSetConverterIconv : public details::CharSetConverterImplBase {
+  class UniqueIconvT {
+    iconv_t ConvDesc;
+
+  public:
+    operator iconv_t() const { return ConvDesc; }
+    UniqueIconvT(iconv_t CD) : ConvDesc(CD) {}
+    ~UniqueIconvT() {
+      if (ConvDesc != (iconv_t)-1) {
+        iconv_close(ConvDesc);
+        ConvDesc = (iconv_t)-1;
+      }
+    }
+    UniqueIconvT(UniqueIconvT &&Other) : ConvDesc(Other.ConvDesc) {
+      Other.ConvDesc = (iconv_t)-1;
+    }
+    UniqueIconvT &operator=(UniqueIconvT &&Other) {
+      if (&Other != this) {
+        ConvDesc = Other.ConvDesc;
+        Other.ConvDesc = (iconv_t)-1;
+      }
+      return *this;
+    }
+  };
+  UniqueIconvT ConvDesc;
+
+public:
+  CharSetConverterIconv(UniqueIconvT ConvDesc)
+      : ConvDesc(std::move(ConvDesc)) {}
+
+  std::error_code convertString(StringRef Source,
+                                SmallVectorImpl<char> &Result) override;
+
+  void reset() override;
+};
+
+std::error_code
+CharSetConverterIconv::convertString(StringRef Source,
+                                     SmallVectorImpl<char> &Result) {
+  // Setup the output. We directly write into the SmallVector.
+  size_t Capacity = Result.capacity();
+  char *Output = static_cast<char *>(Result.data());
+  size_t OutputLength = Capacity;
+  Result.resize_for_overwrite(Capacity);
+
+  size_t Ret;
+  // Handle errors returned from iconv().
+  auto HandleError = [&Capacity, &Output, &OutputLength, &Result,
+                      this](size_t Ret) {
+    if (Ret == static_cast<size_t>(-1)) {
+      // An error occured. Check if we can gracefully handle it.
+      if (errno == E2BIG && Capacity < std::numeric_limits<size_t>::max()) {
+        HandleOverflow(Capacity, Output, OutputLength, Result);
+        // Reset converter
+        iconv(ConvDesc, nullptr, nullptr, nullptr, nullptr);
+        return std::error_code();
+      } else {
+        // Some other error occured.
+        Result.resize(Output - Result.data());
+        return std::error_code(errno, std::generic_category());
+      }
+    } else {
+      // A positive return value indicates that some characters were converted
+      // in a nonreversible way, that is, replaced with a SUB symbol. Returning
+      // an error in this case makes sure that both conversion routines behave
+      // in the same way.
+      return std::make_error_code(std::errc::illegal_byte_sequence);
+    }
+  };
+
+  do {
+    // Setup the input. Use nullptr to reset iconv state if input length is
+    // zero.
+    size_t InputLength = Source.size();
+    char *Input = InputLength ? const_cast<char *>(Source.data()) : nullptr;
+    Ret = iconv(ConvDesc, &Input, &InputLength, &Output, &OutputLength);
+    if (Ret != 0) {
+      if (auto EC = HandleError(Ret))
+        return EC;
+      continue;
+    }
+    // Flush the converter
+    Ret = iconv(ConvDesc, nullptr, nullptr, &Output, &OutputLength);
+    if (Ret != 0) {
+      if (auto EC = HandleError(Ret))
+        return EC;
+      continue;
+    }
+    break;
+  } while (true);
+
+  // Re-adjust size to actual size.
+  Result.resize(Output - Result.data());
+  return std::error_code();
+}
+
+void CharSetConverterIconv::reset() {
+  iconv(ConvDesc, nullptr, nullptr, nullptr, nullptr);
+}
+
+#endif // HAVE_ICONV
+} // namespace
+
+ErrorOr<CharSetConverter> CharSetConverter::create(text_encoding::id CPFrom,
+                                                   text_encoding::id CPTo) {
+
+  assert(CPFrom != CPTo && "Text encodings should be distinct");
+
+  ConversionType Conversion;
+  if (CPFrom == text_encoding::id::UTF8 && CPTo == text_encoding::id::IBM1047)
+    Conversion = UTF8ToIBM1047;
+  else if (CPFrom == text_encoding::id::IBM1047 &&
+           CPTo == text_encoding::id::UTF8)
+    Conversion = IBM1047ToUTF8;
+  else
+    return std::error_code(errno, std::generic_category());
+
+  std::unique_ptr<details::CharSetConverterImplBase> Converter =
+      std::make_unique<CharSetConverterTable>(Conversion);
+  return CharSetConverter(std::move(Converter));
+}
+
+ErrorOr<CharSetConverter> CharSetConverter::create(StringRef CSFrom,
+                                                   StringRef CSTo) {
+  std::optional<text_encoding::id> From = getKnownCharSet(CSFrom);
+  std::optional<text_encoding::id> To = getKnownCharSet(CSTo);
+  if (From && To) {
+    ErrorOr<CharSetConverter> Converter = create(*From, *To);
+    if (Converter)
+      return Converter;
+  }
+#ifdef HAVE_ICU
+  UErrorCode EC = U_ZERO_ERROR;
+  UConverterUniquePtr FromConvDesc(ucnv_open(CSFrom.str().c_str(), &EC));
+  if (U_FAILURE(EC)) {
+    return std::error_code(errno, std::generic_category());
+  }
+  UConverterUniquePtr ToConvDesc(ucnv_open(CSTo.str().c_str(), &EC));
+  if (U_FAILURE(EC)) {
+    return std::error_code(errno, std::generic_category());
+  }
+  std::unique_ptr<details::CharSetConverterImplBase> Converter =
+      std::make_unique<CharSetConverterICU>(std::move(FromConvDesc),
+                                            std::move(ToConvDesc));
+  return CharSetConverter(std::move(Converter));
+#elif defined(HAVE_ICONV)
+  iconv_t ConvDesc = iconv_open(CSTo.str().c_str(), CSFrom.str().c_str());
+  if (ConvDesc == (iconv_t)-1)
+    return std::error_code(errno, std::generic_category());
+  std::unique_ptr<details::CharSetConverterImplBase> Converter =
+      std::make_unique<CharSetConverterIconv>(ConvDesc);
+  return CharSetConverter(std::move(Converter));
+#else
+  return std::make_error_code(std::errc::invalid_argument);
+#endif
+}
diff --git a/llvm/unittests/Support/CMakeLists.txt b/llvm/unittests/Support/CMakeLists.txt
index 6c4e7cb689b20..d6e34fdaba4e7 100644
--- a/llvm/unittests/Support/CMakeLists.txt
+++ b/llvm/unittests/Support/CMakeLists.txt
@@ -17,6 +17,7 @@ add_llvm_unittest(SupportTests
   BalancedPartitioningTest.cpp
   BranchProbabilityTest.cpp
   CachePruningTest.cpp
+  CharSetTest.cpp
   CrashRecoveryTest.cpp
   Casting.cpp
   CheckedArithmeticTest.cpp
diff --git a/llvm/unittests/Support/CharSetTest.cpp b/llvm/unittests/Support/CharSetTest.cpp
new file mode 100644
index 0000000000000..772d46ec73497
--- /dev/null
+++ b/llvm/unittests/Support/CharSetTest.cpp
@@ -0,0 +1,232 @@
+//===- unittests/Support/CharSetTest.cpp - Charset conversion tests -------===//
+//
+// 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 "llvm/Support/CharSet.h"
+#include "llvm/ADT/SmallString.h"
+#include "gtest/gtest.h"
+using namespace llvm;
+
+namespace {
+
+// String "Hello World!"
+static const char HelloA[] =
+    "\x48\x65\x6C\x6C\x6F\x20\x57\x6F\x72\x6C\x64\x21\x0a";
+static const char HelloE[] =
+    "\xC8\x85\x93\x93\x96\x40\xE6\x96\x99\x93\x84\x5A\x15";
+
+// String "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
+static const char ABCStrA[] =
+    "\x41\x42\x43\x44\x45\x46\x47\x48\x49\x4A\x4B\x4C\x4D\x4E\x4F\x50\x51\x52"
+    "\x53\x54\x55\x56\x57\x58\x59\x5A\x61\x62\x63\x64\x65\x66\x67\x68\x69\x6A"
+    "\x6B\x6C\x6D\x6E\x6F\x70\x71\x72\x73\x74\x75\x76\x77\x78\x79\x7A";
+static const char ABCStrE[] =
+    "\xC1\xC2\xC3\xC4\xC5\xC6\xC7\xC8\xC9\xD1\xD2\xD3\xD4\xD5\xD6\xD7\xD8\xD9"
+    "\xE2\xE3\xE4\xE5\xE6\xE7\xE8\xE9\x81\x82\x83\x84\x85\x86\x87\x88\x89\x91"
+    "\x92\x93\x94\x95\x96\x97\x98\x99\xA2\xA3\xA4\xA5\xA6\xA7\xA8\xA9";
+
+// String "¡¢£AÄÅÆEÈÉÊaàáâãäeèéêë"
+static const char AccentUTF[] =
+    "\xc2\xa1\xc2\xa2\xc2\xa3\x41\xc3\x84\xc3\x85\xc3\x86\x45\xc3\x88\xc3\x89"
+    "\xc3\x8a\x61\xc3\xa0\xc3\xa1\xc3\xa2\xc3\xa3\xc3\xa4\x65\xc3\xa8\xc3\xa9"
+    "\xc3\xaa\xc3\xab";
+static const char AccentE[] = "\xaa\x4a\xb1\xc1\x63\x67\x9e\xc5\x74\x71\x72"
+                              "\x81\x44\x45\x42\x46\x43\x85\x54\x51\x52\x53";
+
+// String with Cyrillic character ya.
+static const char CyrillicUTF[] = "\xd0\xaf";
+
+// String "Earth地球".
+// ISO-2022-JP: Sequence ESC $ B (\x1B\x24\x42) switches to JIS X 0208-1983, and
+// sequence ESC ( B (\x1B\x28\x42) switches back to ASCII.
+// IBM-939: Byte 0x0E shifts from single byte to double byte, and 0x0F shifts
+// back.
+static const char EarthUTF[] = "\x45\x61\x72\x74\x68\xe5\x9c\xb0\xe7\x90\x83";
+static const char EarthISO2022[] =
+    "\x45\x61\x72\x74\x68\x1B\x24\x42\x43\x4F\x35\x65\x1B\x28\x42";
+static const char EarthIBM939[] =
+    "\xc5\x81\x99\xa3\x88\x0e\x45\xc2\x48\xdb\x0f";
+static const char EarthUTFExtraPartial[] =
+    "\x45\x61\x72\x74\x68\xe5\x9c\xb0\xe7\x90\x83\xe5";
+
+TEST(CharSet, FromUTF8) {
+  // Hello string.
+  StringRef Src(HelloA);
+  SmallString<64> Dst;
+
+  ErrorOr<CharSetConverter> Conv = CharSetConverter::create(
+      text_encoding::id::UTF8, text_encoding::id::IBM1047);
+
+  // Stop test if conversion is not supported.
+  if (!Conv) {
+    ASSERT_EQ(Conv.getError(),
+              std::make_error_code(std::errc::invalid_argument));
+    return;
+  }
+
+  std::error_code EC = Conv->convert(Src, Dst);
+  EXPECT_TRUE(!EC);
+  EXPECT_STREQ(HelloE, static_cast<std::string>(Dst).c_str());
+  Dst.clear();
+
+  // ABC string.
+  Src = ABCStrA;
+  EC = Conv->convert(Src, Dst);
+  EXPECT_TRUE(!EC);
+  EXPECT_STREQ(ABCStrE, static_cast<std::string>(Dst).c_str());
+  Dst.clear();
+
+  // Accent string.
+  Src = AccentUTF;
+  EC = Conv->convert(Src, Dst);
+  EXPECT_TRUE(!EC);
+  EXPECT_STREQ(AccentE, static_cast<std::string>(Dst).c_str());
+  Dst.clear();
+
+  // Cyrillic string. Results in error because not representable in 1047.
+  Src = CyrillicUTF;
+  EC = Conv->convert(Src, Dst);
+  EXPECT_EQ(EC, std::errc::illegal_byte_sequence);
+}
+
+TEST(CharSet, ToUTF8) {
+  // Hello string.
+  StringRef Src(HelloE);
+  SmallString<64> Dst;
+
+  ErrorOr<CharSetConverter> Conv = CharSetConverter::create(
+      text_encoding::id::IBM1047, text_encoding::id::UTF8);
+
+  // Stop test if conversion is not supported.
+  if (!Conv) {
+    ASSERT_EQ(Conv.getError(),
+              std::make_error_code(std::errc::invalid_argument));
+    return;
+  }
+
+  std::error_code EC = Conv->convert(Src, Dst);
+
+  EXPECT_TRUE(!EC);
+  EXPECT_STREQ(HelloA, static_cast<std::string>(Dst).c_str());
+  Dst.clear();
+
+  // ABC string.
+  Src = ABCStrE;
+  EC = Conv->convert(Src, Dst);
+  EXPECT_TRUE(!EC);
+  EXPECT_STREQ(ABCStrA, static_cast<std::string>(Dst).c_str());
+  Dst.clear();
+
+  // Accent string.
+  Src = AccentE;
+  EC = Conv->convert(Src, Dst);
+  EXPECT_TRUE(!EC);
+  EXPECT_STREQ(AccentUTF, static_cast<std::string>(Dst).c_str());
+}
+
+TEST(CharSet, RoundTrip) {
+  ErrorOr<CharSetConverter> ConvToUTF16 =
+      CharSetConverter::create("IBM-1047", "UTF-16");
+  // Stop test if conversion is not supported (no underlying iconv support).
+  if (!ConvToUTF16) {
+    ASSERT_EQ(ConvToUTF16.getError(),
+              std::make_error_code(std::errc::invalid_argument));
+    return;
+  }
+  ErrorOr<CharSetConverter> ConvToUTF32 =
+      CharSetConverter::create("UTF-16", "UTF-32");
+  // Stop test if conversion is not supported (no underlying iconv support).
+  if (!ConvToUTF32) {
+    ASSERT_EQ(ConvToUTF32.getError(),
+              std::make_error_code(std::errc::invalid_argument));
+    return;
+  }
+  ErrorOr<CharSetConverter> ConvToEBCDIC =
+      CharSetConverter::create("UTF-32", "IBM-1047");
+  // Stop test if conversion is not supported (no underlying iconv support).
+  if (!ConvToEBCDIC) {
+    ASSERT_EQ(ConvToEBCDIC.getError(),
+              std::make_error_code(std::errc::invalid_argument));
+    return;
+  }
+
+  // Setup source string.
+  char SrcStr[256];
+  for (size_t I = 0; I < 256; ++I)
+    SrcStr[I] = (I + 1) % 256;
+
+  SmallString<99> Dst1Str, Dst2Str, Dst3Str;
+
+  std::error_code EC = ConvToUTF16->convert(StringRef(SrcStr), Dst1Str);
+  EXPECT_TRUE(!EC);
+  EC = ConvToUTF32->convert(Dst1Str, Dst2Str);
+  EXPECT_TRUE(!EC);
+  EC = ConvToEBCDIC->convert(Dst2Str, Dst3Str);
+  EXPECT_TRUE(!EC);
+  EXPECT_STREQ(SrcStr, static_cast<std::string>(Dst3Str).c_str());
+}
+
+TEST(CharSet, ShiftState2022) {
+  // Earth string.
+  StringRef Src(EarthUTF);
+  SmallString<8> Dst;
+
+  ErrorOr<CharSetConverter> ConvTo2022 =
+      CharSetConverter::create("UTF-8", "ISO-2022-JP");
+  // Stop test if conversion is not supported (no underlying iconv support).
+  if (!ConvTo2022) {
+    ASSERT_EQ(ConvTo2022.getError(),
+              std::make_error_code(std::errc::invalid_argument));
+    return;
+  }
+
+  // Check that the string is properly converted.
+  std::error_code EC = ConvTo2022->convert(Src, Dst);
+  EXPECT_TRUE(!EC);
+  EXPECT_STREQ(EarthISO2022, static_cast<std::string>(Dst).c_str());
+}
+
+TEST(CharSet, ShiftState2022Partial) {
+  // Earth string.
+  StringRef Src(EarthUTFExtraPartial);
+  SmallString<8> Dst;
+
+  ErrorOr<CharSetConverter> ConvTo2022 =
+      CharSetConverter::create("UTF-8", "ISO-2022-JP");
+  // Stop test if conversion is not supported (no underlying iconv support).
+  if (!ConvTo2022) {
+    ASSERT_EQ(ConvTo2022.getError(),
+              std::make_error_code(std::errc::invalid_argument));
+    return;
+  }
+
+  // Check that the string is properly converted.
+  std::error_code EC = ConvTo2022->convert(Src, Dst);
+  EXPECT_TRUE(EC);
+}
+
+TEST(CharSet, ShiftStateIBM939) {
+  // Earth string.
+  StringRef Src(EarthUTF);
+  SmallString<64> Dst;
+
+  ErrorOr<CharSetConverter> ConvToIBM939 =
+      CharSetConverter::create("UTF-8", "IBM-939");
+  // Stop test if conversion is not supported (no underlying iconv support).
+  if (!ConvToIBM939) {
+    ASSERT_EQ(ConvToIBM939.getError(),
+              std::make_error_code(std::errc::invalid_argument));
+    return;
+  }
+
+  // Check that the string is properly converted.
+  std::error_code EC = ConvToIBM939->convert(Src, Dst);
+  EXPECT_TRUE(!EC);
+  EXPECT_STREQ(EarthIBM939, static_cast<std::string>(Dst).c_str());
+}
+
+} // namespace
diff --git a/llvm/unittests/Support/ConvertEBCDICTest.cpp b/llvm/unittests/Support/ConvertEBCDICTest.cpp
index eec76879ac92c..557f29c391f9c 100644
--- a/llvm/unittests/Support/ConvertEBCDICTest.cpp
+++ b/llvm/unittests/Support/ConvertEBCDICTest.cpp
@@ -41,7 +41,7 @@ static const char AccentE[] = "\xaa\x4a\xb1\xc1\x63\x67\x9e\xc5\x74\x71\x72"
 // String with Cyrillic character ya.
 static const char CyrillicUTF[] = "\xd0\xaf";
 
-TEST(CharSet, FromUTF8) {
+TEST(ConverterEBCDIC, convertToEBCDIC) {
   // Hello string.
   StringRef Src(HelloA);
   SmallString<64> Dst;
@@ -72,7 +72,7 @@ TEST(CharSet, FromUTF8) {
   Dst.clear();
 }
 
-TEST(CharSet, ToUTF8) {
+TEST(ConverterEBCDIC, convertFromEBCDIC) {
   // Hello string.
   StringRef Src(HelloE);
   SmallString<64> Dst;