diff --git a/llvm/include/llvm/ADT/APInt.h b/llvm/include/llvm/ADT/APInt.h
--- a/llvm/include/llvm/ADT/APInt.h
+++ b/llvm/include/llvm/ADT/APInt.h
@@ -16,7 +16,9 @@
 #define LLVM_ADT_APINT_H
 
 #include "llvm/Support/Compiler.h"
+#include "llvm/Support/LLVMSupportExports.h"
 #include "llvm/Support/MathExtras.h"
+
 #include <cassert>
 #include <climits>
 #include <cstring>
@@ -67,7 +69,7 @@
 ///   * In general, the class tries to follow the style of computation that LLVM
 ///     uses in its IR. This simplifies its use for LLVM.
 ///
-class LLVM_NODISCARD APInt {
+class LLVM_SUPPORT_ABI LLVM_NODISCARD APInt {
 public:
   typedef uint64_t WordType;
 
diff --git a/llvm/include/llvm/ADT/EpochTracker.h b/llvm/include/llvm/ADT/EpochTracker.h
--- a/llvm/include/llvm/ADT/EpochTracker.h
+++ b/llvm/include/llvm/ADT/EpochTracker.h
@@ -16,6 +16,7 @@
 #define LLVM_ADT_EPOCHTRACKER_H
 
 #include "llvm/Config/abi-breaking.h"
+#include "llvm/Support/LLVMSupportExports.h"
 
 #include <cstdint>
 
@@ -32,7 +33,7 @@
 /// isHandleInSync at appropriate points to assert that the handle they're using
 /// is still valid.
 ///
-class DebugEpochBase {
+class LLVM_SUPPORT_ABI DebugEpochBase {
   uint64_t Epoch;
 
 public:
@@ -78,7 +79,7 @@
 
 #else
 
-class DebugEpochBase {
+class LLVM_SUPPORT_ABI DebugEpochBase {
 public:
   void incrementEpoch() {}
 
diff --git a/llvm/include/llvm/ADT/FoldingSet.h b/llvm/include/llvm/ADT/FoldingSet.h
--- a/llvm/include/llvm/ADT/FoldingSet.h
+++ b/llvm/include/llvm/ADT/FoldingSet.h
@@ -18,6 +18,8 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/iterator.h"
 #include "llvm/Support/Allocator.h"
+#include "llvm/Support/LLVMSupportExports.h"
+
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
@@ -109,7 +111,7 @@
 /// in the bucket via a singly linked list.  The last node in the list points
 /// back to the bucket to facilitate node removal.
 ///
-class FoldingSetBase {
+class LLVM_SUPPORT_ABI FoldingSetBase {
 protected:
   /// Buckets - Array of bucket chains.
   void **Buckets;
@@ -310,7 +312,7 @@
 /// FoldingSetNodeID - This class is used to gather all the unique data bits of
 /// a node.  When all the bits are gathered this class is used to produce a
 /// hash value for the node.
-class FoldingSetNodeID {
+class LLVM_SUPPORT_ABI FoldingSetNodeID {
   /// Bits - Vector of all the data bits that make the node unique.
   /// Use a SmallVector to avoid a heap allocation in the common case.
   SmallVector<unsigned, 32> Bits;
diff --git a/llvm/include/llvm/ADT/IntEqClasses.h b/llvm/include/llvm/ADT/IntEqClasses.h
--- a/llvm/include/llvm/ADT/IntEqClasses.h
+++ b/llvm/include/llvm/ADT/IntEqClasses.h
@@ -21,10 +21,11 @@
 #define LLVM_ADT_INTEQCLASSES_H
 
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/LLVMSupportExports.h"
 
 namespace llvm {
 
-class IntEqClasses {
+class LLVM_SUPPORT_ABI IntEqClasses {
   /// EC - When uncompressed, map each integer to a smaller member of its
   /// equivalence class. The class leader is the smallest member and maps to
   /// itself.
diff --git a/llvm/include/llvm/ADT/SmallPtrSet.h b/llvm/include/llvm/ADT/SmallPtrSet.h
--- a/llvm/include/llvm/ADT/SmallPtrSet.h
+++ b/llvm/include/llvm/ADT/SmallPtrSet.h
@@ -16,8 +16,10 @@
 
 #include "llvm/ADT/EpochTracker.h"
 #include "llvm/Support/Compiler.h"
+#include "llvm/Support/LLVMSupportExports.h"
 #include "llvm/Support/ReverseIteration.h"
 #include "llvm/Support/type_traits.h"
+
 #include <cassert>
 #include <cstddef>
 #include <cstdlib>
@@ -46,7 +48,7 @@
 /// (-2), to allow deletion.  The hash table is resized when the table is 3/4 or
 /// more.  When this happens, the table is doubled in size.
 ///
-class SmallPtrSetImplBase : public DebugEpochBase {
+class LLVM_SUPPORT_ABI SmallPtrSetImplBase : public DebugEpochBase {
   friend class SmallPtrSetIteratorImpl;
 
 protected:
diff --git a/llvm/include/llvm/ADT/StringExtras.h b/llvm/include/llvm/ADT/StringExtras.h
--- a/llvm/include/llvm/ADT/StringExtras.h
+++ b/llvm/include/llvm/ADT/StringExtras.h
@@ -18,6 +18,8 @@
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/Twine.h"
+#include "llvm/Support/LLVMSupportExports.h"
+
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
@@ -319,11 +321,13 @@
 /// there are no tokens in the source string, an empty string is returned.
 /// The function returns a pair containing the extracted token and the
 /// remaining tail string.
+LLVM_SUPPORT_ABI
 std::pair<StringRef, StringRef> getToken(StringRef Source,
                                          StringRef Delimiters = " \t\n\v\f\r");
 
 /// SplitString - Split up the specified string according to the specified
 /// delimiters, appending the result fragments to the output list.
+LLVM_SUPPORT_ABI
 void SplitString(StringRef Source,
                  SmallVectorImpl<StringRef> &OutFragments,
                  StringRef Delimiters = " \t\n\v\f\r");
diff --git a/llvm/include/llvm/ADT/StringMap.h b/llvm/include/llvm/ADT/StringMap.h
--- a/llvm/include/llvm/ADT/StringMap.h
+++ b/llvm/include/llvm/ADT/StringMap.h
@@ -15,6 +15,7 @@
 
 #include "llvm/ADT/StringMapEntry.h"
 #include "llvm/Support/AllocatorBase.h"
+#include "llvm/Support/LLVMSupportExports.h"
 #include "llvm/Support/PointerLikeTypeTraits.h"
 #include <initializer_list>
 #include <iterator>
@@ -27,7 +28,7 @@
 
 /// StringMapImpl - This is the base class of StringMap that is shared among
 /// all of its instantiations.
-class StringMapImpl {
+class LLVM_SUPPORT_ABI StringMapImpl {
 protected:
   // Array of NumBuckets pointers to entries, null pointers are holes.
   // TheTable[NumBuckets] contains a sentinel value for easy iteration. Followed
diff --git a/llvm/include/llvm/ADT/StringRef.h b/llvm/include/llvm/ADT/StringRef.h
--- a/llvm/include/llvm/ADT/StringRef.h
+++ b/llvm/include/llvm/ADT/StringRef.h
@@ -12,6 +12,8 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/Support/Compiler.h"
+#include "llvm/Support/LLVMSupportExports.h"
+
 #include <algorithm>
 #include <cassert>
 #include <cstddef>
@@ -39,11 +41,13 @@
   class StringRef;
 
   /// Helper functions for StringRef::getAsInteger.
+  LLVM_SUPPORT_ABI
   bool getAsUnsignedInteger(StringRef Str, unsigned Radix,
                             unsigned long long &Result);
 
   bool getAsSignedInteger(StringRef Str, unsigned Radix, long long &Result);
 
+  LLVM_SUPPORT_ABI
   bool consumeUnsignedInteger(StringRef &Str, unsigned Radix,
                               unsigned long long &Result);
   bool consumeSignedInteger(StringRef &Str, unsigned Radix, long long &Result);
@@ -55,7 +59,7 @@
   /// situations where the character data resides in some other buffer, whose
   /// lifetime extends past that of the StringRef. For this reason, it is not in
   /// general safe to store a StringRef.
-  class LLVM_GSL_POINTER StringRef {
+  class LLVM_SUPPORT_ABI LLVM_GSL_POINTER StringRef {
   public:
     static constexpr size_t npos = ~size_t(0);
 
@@ -945,7 +949,7 @@
   /// @}
 
   /// Compute a hash_code for a StringRef.
-  LLVM_NODISCARD
+  LLVM_SUPPORT_ABI LLVM_NODISCARD
   hash_code hash_value(StringRef S);
 
   // Provide DenseMapInfo for StringRefs.
diff --git a/llvm/include/llvm/ADT/Twine.h b/llvm/include/llvm/ADT/Twine.h
--- a/llvm/include/llvm/ADT/Twine.h
+++ b/llvm/include/llvm/ADT/Twine.h
@@ -12,6 +12,8 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/LLVMSupportExports.h"
+
 #include <cassert>
 #include <cstdint>
 #include <string>
@@ -80,7 +82,7 @@
   /// so we provide two additional methods (and accompanying operator+
   /// overloads) to guarantee that particularly important cases (cstring plus
   /// StringRef) codegen as desired.
-  class Twine {
+  class LLVM_SUPPORT_ABI Twine {
     /// NodeKind - Represent the type of an argument.
     enum NodeKind : unsigned char {
       /// An empty string; the result of concatenating anything with it is also
diff --git a/llvm/include/llvm/Support/CodeGenCoverage.h b/llvm/include/llvm/Support/CodeGenCoverage.h
--- a/llvm/include/llvm/Support/CodeGenCoverage.h
+++ b/llvm/include/llvm/Support/CodeGenCoverage.h
@@ -12,12 +12,13 @@
 #define LLVM_SUPPORT_CODEGENCOVERAGE_H
 
 #include "llvm/ADT/BitVector.h"
+#include "llvm/Support/LLVMSupportExports.h"
 
 namespace llvm {
 class LLVMContext;
 class MemoryBuffer;
 
-class CodeGenCoverage {
+class LLVM_SUPPORT_ABI CodeGenCoverage {
 protected:
   BitVector RuleCoverage;
 
diff --git a/llvm/include/llvm/Support/CommandLine.h b/llvm/include/llvm/Support/CommandLine.h
--- a/llvm/include/llvm/Support/CommandLine.h
+++ b/llvm/include/llvm/Support/CommandLine.h
@@ -30,8 +30,10 @@
 #include "llvm/ADT/Twine.h"
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/LLVMSupportExports.h"
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/raw_ostream.h"
+
 #include <cassert>
 #include <climits>
 #include <cstddef>
@@ -68,6 +70,7 @@
 // that give precedence to later occurrences.  If your program supports options
 // that give precedence to earlier occurrences, you will need to extend this
 // function to support it correctly.
+LLVM_SUPPORT_ABI
 bool ParseCommandLineOptions(int argc, const char *const *argv,
                              StringRef Overview = "",
                              raw_ostream *Errs = nullptr,
@@ -109,6 +112,7 @@
 ///
 /// Literal options are used by some parsers to register special option values.
 /// This is how the PassNameParser registers pass names for opt.
+LLVM_SUPPORT_ABI
 void AddLiteralOption(Option &O, StringRef Name);
 
 //===----------------------------------------------------------------------===//
@@ -183,7 +187,7 @@
 //===----------------------------------------------------------------------===//
 // Option Category class
 //
-class OptionCategory {
+class LLVM_SUPPORT_ABI OptionCategory {
 private:
   StringRef const Name;
   StringRef const Description;
@@ -246,7 +250,7 @@
 //===----------------------------------------------------------------------===//
 // Option Base class
 //
-class Option {
+class LLVM_SUPPORT_ABI Option {
   friend class alias;
 
   // handleOccurrences - Overriden by subclasses to handle the value passed into
@@ -519,7 +523,7 @@
 // OptionValue class
 
 // Support value comparison outside the template.
-struct GenericOptionValue {
+struct LLVM_SUPPORT_ABI GenericOptionValue {
   virtual bool compare(const GenericOptionValue &V) const = 0;
 
 protected:
@@ -642,7 +646,7 @@
 };
 
 template <>
-struct OptionValue<std::string> final : OptionValueCopy<std::string> {
+struct LLVM_SUPPORT_ABI OptionValue<std::string> final : OptionValueCopy<std::string> {
   using WrapperType = StringRef;
 
   OptionValue() = default;
@@ -712,7 +716,7 @@
 // not need replicated for every instance of the generic parser.  This also
 // allows us to put stuff into CommandLine.cpp
 //
-class generic_parser_base {
+class LLVM_SUPPORT_ABI generic_parser_base {
 protected:
   class GenericOptionInfo {
   public:
@@ -875,7 +879,7 @@
 //--------------------------------------------------
 // basic_parser - Super class of parsers to provide boilerplate code
 //
-class basic_parser_impl { // non-template implementation of basic_parser<t>
+class LLVM_SUPPORT_ABI basic_parser_impl { // non-template implementation of basic_parser<t>
 public:
   basic_parser_impl(Option &) {}
 
@@ -926,7 +930,7 @@
 //--------------------------------------------------
 // parser<bool>
 //
-template <> class parser<bool> : public basic_parser<bool> {
+template <> class LLVM_SUPPORT_ABI parser<bool> : public basic_parser<bool> {
 public:
   parser(Option &O) : basic_parser(O) {}
 
@@ -1045,7 +1049,7 @@
 //--------------------------------------------------
 // parser<unsigned>
 //
-template <> class parser<unsigned> : public basic_parser<unsigned> {
+template <> class LLVM_SUPPORT_ABI parser<unsigned> : public basic_parser<unsigned> {
 public:
   parser(Option &O) : basic_parser(O) {}
 
@@ -1158,7 +1162,7 @@
 //--------------------------------------------------
 // parser<std::string>
 //
-template <> class parser<std::string> : public basic_parser<std::string> {
+template <> class LLVM_SUPPORT_ABI parser<std::string> : public basic_parser<std::string> {
 public:
   parser(Option &O) : basic_parser(O) {}
 
diff --git a/llvm/include/llvm/Support/Debug.h b/llvm/include/llvm/Support/Debug.h
--- a/llvm/include/llvm/Support/Debug.h
+++ b/llvm/include/llvm/Support/Debug.h
@@ -28,6 +28,8 @@
 #ifndef LLVM_SUPPORT_DEBUG_H
 #define LLVM_SUPPORT_DEBUG_H
 
+#include "llvm/Support/LLVMSupportExports.h"
+
 namespace llvm {
 
 class raw_ostream;
@@ -110,7 +112,7 @@
 /// dbgs() - This returns a reference to a raw_ostream for debugging
 /// messages.  If debugging is disabled it returns errs().  Use it
 /// like: dbgs() << "foo" << "bar";
-raw_ostream &dbgs();
+LLVM_SUPPORT_ABI raw_ostream &dbgs();
 
 // DEBUG macro - This macro should be used by passes to emit debug information.
 // In the '-debug' option is specified on the commandline, and if this is a
diff --git a/llvm/include/llvm/Support/Error.h b/llvm/include/llvm/Support/Error.h
--- a/llvm/include/llvm/Support/Error.h
+++ b/llvm/include/llvm/Support/Error.h
@@ -25,7 +25,9 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/ErrorOr.h"
 #include "llvm/Support/Format.h"
+#include "llvm/Support/LLVMSupportExports.h"
 #include "llvm/Support/raw_ostream.h"
+
 #include <algorithm>
 #include <cassert>
 #include <cstdint>
@@ -45,7 +47,7 @@
 
 /// Base class for error info classes. Do not extend this directly: Extend
 /// the ErrorInfo template subclass instead.
-class ErrorInfoBase {
+class LLVM_SUPPORT_ABI ErrorInfoBase {
 public:
   virtual ~ErrorInfoBase() = default;
 
@@ -719,7 +721,7 @@
 
 /// Report a serious error, calling any installed error handler. See
 /// ErrorHandling.h.
-[[noreturn]] void report_fatal_error(Error Err, bool gen_crash_diag = true);
+[[noreturn]] void LLVM_SUPPORT_ABI report_fatal_error(Error Err, bool gen_crash_diag = true);
 
 /// Report a fatal error if Err is a failure value.
 ///
@@ -1156,7 +1158,7 @@
 /// sensible conversion to std::error_code is available, as attempts to convert
 /// to/from this error will result in a fatal error. (i.e. it is a programmatic
 ///error to try to convert such a value).
-std::error_code inconvertibleErrorCode();
+LLVM_SUPPORT_ABI std::error_code inconvertibleErrorCode();
 
 /// Helper for converting an std::error_code to a Error.
 Error errorCodeToError(std::error_code EC);
@@ -1205,7 +1207,7 @@
 ///   }
 ///   @endcode
 ///
-class StringError : public ErrorInfo<StringError> {
+class LLVM_SUPPORT_ABI StringError : public ErrorInfo<StringError> {
 public:
   static char ID;
 
diff --git a/llvm/include/llvm/Support/Format.h b/llvm/include/llvm/Support/Format.h
--- a/llvm/include/llvm/Support/Format.h
+++ b/llvm/include/llvm/Support/Format.h
@@ -26,6 +26,8 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/DataTypes.h"
+#include "llvm/Support/LLVMSupportExports.h"
+
 #include <cassert>
 #include <cstdio>
 #include <tuple>
@@ -35,7 +37,7 @@
 
 /// This is a helper class used for handling formatted output.  It is the
 /// abstract base class of a templated derived class.
-class format_object_base {
+class LLVM_SUPPORT_ABI format_object_base {
 protected:
   const char *Fmt;
   ~format_object_base() = default; // Disallow polymorphic deletion.
diff --git a/llvm/include/llvm/Support/FormatVariadicDetails.h b/llvm/include/llvm/Support/FormatVariadicDetails.h
--- a/llvm/include/llvm/Support/FormatVariadicDetails.h
+++ b/llvm/include/llvm/Support/FormatVariadicDetails.h
@@ -10,6 +10,7 @@
 #define LLVM_SUPPORT_FORMATVARIADICDETAILS_H
 
 #include "llvm/ADT/StringRef.h"
+#include "llvm/Support/LLVMSupportExports.h"
 #include "llvm/Support/raw_ostream.h"
 
 #include <type_traits>
@@ -19,7 +20,7 @@
 class Error;
 
 namespace detail {
-class format_adapter {
+class LLVM_SUPPORT_ABI format_adapter {
   virtual void anchor();
 
 protected:
diff --git a/llvm/include/llvm/Support/FormattedStream.h b/llvm/include/llvm/Support/FormattedStream.h
--- a/llvm/include/llvm/Support/FormattedStream.h
+++ b/llvm/include/llvm/Support/FormattedStream.h
@@ -15,7 +15,9 @@
 #define LLVM_SUPPORT_FORMATTEDSTREAM_H
 
 #include "llvm/ADT/SmallString.h"
+#include "llvm/Support/LLVMSupportExports.h"
 #include "llvm/Support/raw_ostream.h"
+
 #include <utility>
 
 namespace llvm {
@@ -27,7 +29,7 @@
 /// doesn't attempt to handle everything Unicode can do (combining characters,
 /// right-to-left markers, etc), but should cover the cases likely to appear in
 /// source code or diagnostic messages.
-class formatted_raw_ostream : public raw_ostream {
+class LLVM_SUPPORT_ABI formatted_raw_ostream : public raw_ostream {
   /// TheStream - The real stream we output to. We set it to be
   /// unbuffered, since we're already doing our own buffering.
   ///
diff --git a/llvm/include/llvm/Support/InitLLVM.h b/llvm/include/llvm/Support/InitLLVM.h
--- a/llvm/include/llvm/Support/InitLLVM.h
+++ b/llvm/include/llvm/Support/InitLLVM.h
@@ -12,6 +12,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/Allocator.h"
+#include "llvm/Support/LLVMSupportExports.h"
 #include "llvm/Support/PrettyStackTrace.h"
 
 // The main() functions in typical LLVM tools start with InitLLVM which does
@@ -32,7 +33,7 @@
 // InitLLVM calls llvm_shutdown() on destruction, which cleans up
 // ManagedStatic objects.
 namespace llvm {
-class InitLLVM {
+class LLVM_SUPPORT_ABI InitLLVM {
 public:
   InitLLVM(int &Argc, const char **&Argv,
            bool InstallPipeSignalExitHandler = true);
diff --git a/llvm/include/llvm/Support/JSON.h b/llvm/include/llvm/Support/JSON.h
--- a/llvm/include/llvm/Support/JSON.h
+++ b/llvm/include/llvm/Support/JSON.h
@@ -51,7 +51,9 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/FormatVariadic.h"
+#include "llvm/Support/LLVMSupportExports.h"
 #include "llvm/Support/raw_ostream.h"
+
 #include <map>
 
 namespace llvm {
@@ -74,11 +76,11 @@
 
 /// Returns true if \p S is valid UTF-8, which is required for use as JSON.
 /// If it returns false, \p Offset is set to a byte offset near the first error.
-bool isUTF8(llvm::StringRef S, size_t *ErrOffset = nullptr);
+LLVM_SUPPORT_ABI bool isUTF8(llvm::StringRef S, size_t *ErrOffset = nullptr);
 /// Replaces invalid UTF-8 sequences in \p S with the replacement character
 /// (U+FFFD). The returned string is valid UTF-8.
 /// This is much slower than isUTF8, so test that first.
-std::string fixUTF8(llvm::StringRef S);
+LLVM_SUPPORT_ABI std::string fixUTF8(llvm::StringRef S);
 
 class Array;
 class ObjectKey;
@@ -87,7 +89,7 @@
 
 /// An Object is a JSON object, which maps strings to heterogenous JSON values.
 /// It simulates DenseMap<ObjectKey, Value>. ObjectKey is a maybe-owned string.
-class Object {
+class LLVM_SUPPORT_ABI Object {
   using Storage = DenseMap<ObjectKey, Value, llvm::DenseMapInfo<StringRef>>;
   Storage M;
 
@@ -286,7 +288,7 @@
 /// And parsed:
 ///   Expected<Value> E = json::parse("[1, 2, null]");
 ///   assert(E && E->kind() == Value::Array);
-class Value {
+class LLVM_SUPPORT_ABI Value {
 public:
   enum Kind {
     Null,
@@ -883,7 +885,7 @@
 /// This can be mismatched begin()/end() pairs, trying to emit attributes inside
 /// an array, and so on.
 /// With asserts disabled, this is undefined behavior.
-class OStream {
+class LLVM_SUPPORT_ABI OStream {
  public:
   using Block = llvm::function_ref<void()>;
   // If IndentSize is nonzero, output is pretty-printed.
diff --git a/llvm/include/llvm/Support/LLVMSupportExports.h b/llvm/include/llvm/Support/LLVMSupportExports.h
new file mode 100644
--- /dev/null
+++ b/llvm/include/llvm/Support/LLVMSupportExports.h
@@ -0,0 +1,40 @@
+//===--- SupportMacros.h - ABI Macro Definitions ----------------*- 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_SUPPORT_LLVMSUPPORT_EXPORTS_H
+#define LLVM_SUPPORT_LLVMSUPPORT_EXPORTS_H
+
+#if defined(__ELF__)
+# if defined(LLVM_SUPPORT_STATIC)
+#   define LLVM_SUPPORT_ABI
+# else
+#   if defined(LLVMSupport_EXPORTS)
+#     define LLVM_SUPPORT_ABI __attribute__((__visibility__("protected")))
+#   else
+#     define LLVM_SUPPORT_ABI __attribute__((__visibility__("default")))
+#   endif
+# endif
+#elif defined(__MACH__) || defined(__WASM__)
+# if defined(LLVM_SUPPORT_STATIC)
+#   define LLVM_SUPPORT_ABI
+# else
+#   define LLVM_SUPPORT_ABI __attribute__((__visibility__("default")))
+# endif
+#else
+# if defined(LLVM_SUPPORT_STATIC)
+#   define LLVM_SUPPORT_abi
+# else
+#   if defined(LLVMSupport_EXPORTS)
+#     define LLVM_SUPPORT_ABI __declspec(dllexport)
+#   else
+#     define LLVM_SUPPORT_ABI __declspec(dllimport)
+#   endif
+# endif
+#endif
+
+#endif
diff --git a/llvm/include/llvm/Support/MemAlloc.h b/llvm/include/llvm/Support/MemAlloc.h
--- a/llvm/include/llvm/Support/MemAlloc.h
+++ b/llvm/include/llvm/Support/MemAlloc.h
@@ -18,6 +18,7 @@
 
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/LLVMSupportExports.h"
 #include <cstdlib>
 
 namespace llvm {
@@ -71,7 +72,7 @@
 /// like posix_memalign due to portability. It is mostly intended to allow
 /// compatibility with platforms that, after aligned allocation was added, use
 /// reduced default alignment.
-LLVM_ATTRIBUTE_RETURNS_NONNULL LLVM_ATTRIBUTE_RETURNS_NOALIAS void *
+LLVM_SUPPORT_ABI LLVM_ATTRIBUTE_RETURNS_NONNULL LLVM_ATTRIBUTE_RETURNS_NOALIAS void *
 allocate_buffer(size_t Size, size_t Alignment);
 
 /// Deallocate a buffer of memory with the given size and alignment.
@@ -81,7 +82,7 @@
 ///
 /// The pointer must have been allocated with the corresponding new operator,
 /// most likely using the above helper.
-void deallocate_buffer(void *Ptr, size_t Size, size_t Alignment);
+LLVM_SUPPORT_ABI void deallocate_buffer(void *Ptr, size_t Size, size_t Alignment);
 
 } // namespace llvm
 #endif
diff --git a/llvm/include/llvm/Support/MemoryBuffer.h b/llvm/include/llvm/Support/MemoryBuffer.h
--- a/llvm/include/llvm/Support/MemoryBuffer.h
+++ b/llvm/include/llvm/Support/MemoryBuffer.h
@@ -19,7 +19,9 @@
 #include "llvm/ADT/Twine.h"
 #include "llvm/Support/CBindingWrapping.h"
 #include "llvm/Support/ErrorOr.h"
+#include "llvm/Support/LLVMSupportExports.h"
 #include "llvm/Support/MemoryBufferRef.h"
+
 #include <cstddef>
 #include <cstdint>
 #include <memory>
@@ -47,7 +49,7 @@
 /// be more efficient for clients which are reading all the data to stop
 /// reading when they encounter a '\0' than to continually check the file
 /// position to see if it has reached the end of the file.
-class MemoryBuffer {
+class LLVM_SUPPORT_ABI MemoryBuffer {
   const char *BufferStart; // Start of the buffer.
   const char *BufferEnd;   // End of the buffer.
 
diff --git a/llvm/include/llvm/Support/NativeFormatting.h b/llvm/include/llvm/Support/NativeFormatting.h
--- a/llvm/include/llvm/Support/NativeFormatting.h
+++ b/llvm/include/llvm/Support/NativeFormatting.h
@@ -10,6 +10,8 @@
 #define LLVM_SUPPORT_NATIVEFORMATTING_H
 
 #include "llvm/ADT/Optional.h"
+#include "llvm/Support/LLVMSupportExports.h"
+
 #include <cstdint>
 
 namespace llvm {
@@ -23,22 +25,35 @@
 
 size_t getDefaultPrecision(FloatStyle Style);
 
-bool isPrefixedHexStyle(HexPrintStyle S);
+LLVM_SUPPORT_ABI bool isPrefixedHexStyle(HexPrintStyle S);
 
+LLVM_SUPPORT_ABI
 void write_integer(raw_ostream &S, unsigned int N, size_t MinDigits,
                    IntegerStyle Style);
+
+LLVM_SUPPORT_ABI
 void write_integer(raw_ostream &S, int N, size_t MinDigits, IntegerStyle Style);
+
+LLVM_SUPPORT_ABI
 void write_integer(raw_ostream &S, unsigned long N, size_t MinDigits,
                    IntegerStyle Style);
+
+LLVM_SUPPORT_ABI
 void write_integer(raw_ostream &S, long N, size_t MinDigits,
                    IntegerStyle Style);
+
+LLVM_SUPPORT_ABI
 void write_integer(raw_ostream &S, unsigned long long N, size_t MinDigits,
                    IntegerStyle Style);
+
+LLVM_SUPPORT_ABI
 void write_integer(raw_ostream &S, long long N, size_t MinDigits,
                    IntegerStyle Style);
 
+LLVM_SUPPORT_ABI
 void write_hex(raw_ostream &S, uint64_t N, HexPrintStyle Style,
                Optional<size_t> Width = None);
+
 void write_double(raw_ostream &S, double D, FloatStyle Style,
                   Optional<size_t> Precision = None);
 }
diff --git a/llvm/include/llvm/Support/Regex.h b/llvm/include/llvm/Support/Regex.h
--- a/llvm/include/llvm/Support/Regex.h
+++ b/llvm/include/llvm/Support/Regex.h
@@ -17,6 +17,8 @@
 #define LLVM_SUPPORT_REGEX_H
 
 #include "llvm/ADT/BitmaskEnum.h"
+#include "llvm/Support/LLVMSupportExports.h"
+
 #include <string>
 
 struct llvm_regex;
@@ -25,7 +27,7 @@
   class StringRef;
   template<typename T> class SmallVectorImpl;
 
-  class Regex {
+  class LLVM_SUPPORT_ABI Regex {
   public:
     enum RegexFlags : unsigned {
       NoFlags = 0,
diff --git a/llvm/include/llvm/Support/Signals.h b/llvm/include/llvm/Support/Signals.h
--- a/llvm/include/llvm/Support/Signals.h
+++ b/llvm/include/llvm/Support/Signals.h
@@ -14,6 +14,8 @@
 #ifndef LLVM_SUPPORT_SIGNALS_H
 #define LLVM_SUPPORT_SIGNALS_H
 
+#include "llvm/Support/LLVMSupportExports.h"
+
 #include <string>
 
 namespace llvm {
@@ -24,7 +26,7 @@
 
   /// This function runs all the registered interrupt handlers, including the
   /// removal of files registered by RemoveFileOnSignal.
-  void RunInterruptHandlers();
+  LLVM_SUPPORT_ABI void RunInterruptHandlers();
 
   /// This function registers signal handlers to ensure that if a signal gets
   /// delivered that the named file is removed.
diff --git a/llvm/include/llvm/Support/SourceMgr.h b/llvm/include/llvm/Support/SourceMgr.h
--- a/llvm/include/llvm/Support/SourceMgr.h
+++ b/llvm/include/llvm/Support/SourceMgr.h
@@ -16,8 +16,10 @@
 #define LLVM_SUPPORT_SOURCEMGR_H
 
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/LLVMSupportExports.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/SMLoc.h"
+
 #include <vector>
 
 namespace llvm {
@@ -28,7 +30,7 @@
 
 /// This owns the files read by a parser, handles include stacks,
 /// and handles diagnostic wrangling.
-class SourceMgr {
+class LLVM_SUPPORT_ABI SourceMgr {
 public:
   enum DiagKind {
     DK_Error,
diff --git a/llvm/include/llvm/Support/Timer.h b/llvm/include/llvm/Support/Timer.h
--- a/llvm/include/llvm/Support/Timer.h
+++ b/llvm/include/llvm/Support/Timer.h
@@ -12,6 +12,8 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/DataTypes.h"
+#include "llvm/Support/LLVMSupportExports.h"
+
 #include <cassert>
 #include <string>
 #include <utility>
@@ -79,7 +81,7 @@
 /// when the last timer is destroyed, otherwise it is printed when its
 /// TimerGroup is destroyed.  Timers do not print their information if they are
 /// never started.
-class Timer {
+class LLVM_SUPPORT_ABI Timer {
   TimeRecord Time;          ///< The total time captured.
   TimeRecord StartTime;     ///< The time startTimer() was last called.
   std::string Name;         ///< The name of this time variable.
@@ -173,7 +175,7 @@
 /// report that is printed when the TimerGroup is destroyed.  It is illegal to
 /// destroy a TimerGroup object before all of the Timers in it are gone.  A
 /// TimerGroup can be specified for a newly created timer in its constructor.
-class TimerGroup {
+class LLVM_SUPPORT_ABI TimerGroup {
   struct PrintRecord {
     TimeRecord Time;
     std::string Name;
diff --git a/llvm/include/llvm/Support/ToolOutputFile.h b/llvm/include/llvm/Support/ToolOutputFile.h
--- a/llvm/include/llvm/Support/ToolOutputFile.h
+++ b/llvm/include/llvm/Support/ToolOutputFile.h
@@ -14,6 +14,7 @@
 #define LLVM_SUPPORT_TOOLOUTPUTFILE_H
 
 #include "llvm/ADT/Optional.h"
+#include "llvm/Support/LLVMSupportExports.h"
 #include "llvm/Support/raw_ostream.h"
 
 namespace llvm {
diff --git a/llvm/include/llvm/Support/TypeSize.h b/llvm/include/llvm/Support/TypeSize.h
--- a/llvm/include/llvm/Support/TypeSize.h
+++ b/llvm/include/llvm/Support/TypeSize.h
@@ -16,6 +16,7 @@
 #define LLVM_SUPPORT_TYPESIZE_H
 
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/Support/LLVMSupportExports.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/WithColor.h"
 
@@ -414,7 +415,7 @@
 // TypeSize is used to represent the size of types. If the type is of fixed
 // size, it will represent the exact size. If the type is a scalable vector,
 // it will represent the known minimum size.
-class TypeSize : public LinearPolySize<TypeSize> {
+class LLVM_SUPPORT_ABI TypeSize : public LinearPolySize<TypeSize> {
 public:
   TypeSize(const LinearPolySize<TypeSize> &V) : LinearPolySize(V) {}
   TypeSize(ScalarTy MinVal, bool IsScalable)
diff --git a/llvm/include/llvm/Support/WithColor.h b/llvm/include/llvm/Support/WithColor.h
--- a/llvm/include/llvm/Support/WithColor.h
+++ b/llvm/include/llvm/Support/WithColor.h
@@ -9,6 +9,7 @@
 #ifndef LLVM_SUPPORT_WITHCOLOR_H
 #define LLVM_SUPPORT_WITHCOLOR_H
 
+#include "llvm/Support/LLVMSupportExports.h"
 #include "llvm/Support/raw_ostream.h"
 
 namespace llvm {
@@ -50,7 +51,7 @@
 
 /// An RAII object that temporarily switches an output stream to a specific
 /// color.
-class WithColor {
+class LLVM_SUPPORT_ABI WithColor {
   raw_ostream &OS;
   ColorMode Mode;
 
diff --git a/llvm/include/llvm/Support/raw_ostream.h b/llvm/include/llvm/Support/raw_ostream.h
--- a/llvm/include/llvm/Support/raw_ostream.h
+++ b/llvm/include/llvm/Support/raw_ostream.h
@@ -16,6 +16,8 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/DataTypes.h"
+#include "llvm/Support/LLVMSupportExports.h"
+
 #include <cassert>
 #include <chrono>
 #include <cstddef>
@@ -50,7 +52,7 @@
 /// output to a stream.  It does not support seeking, reopening, rewinding, line
 /// buffered disciplines etc. It is a simple buffer that outputs
 /// a chunk at a time.
-class raw_ostream {
+class LLVM_SUPPORT_ABI raw_ostream {
 public:
   // Class kinds to support LLVM-style RTTI.
   enum class OStreamKind {
@@ -412,7 +414,7 @@
 /// An abstract base class for streams implementations that also support a
 /// pwrite operation. This is useful for code that can mostly stream out data,
 /// but needs to patch in a header that needs to know the output size.
-class raw_pwrite_stream : public raw_ostream {
+class LLVM_SUPPORT_ABI raw_pwrite_stream : public raw_ostream {
   virtual void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) = 0;
   void anchor() override;
 
@@ -438,7 +440,7 @@
 
 /// A raw_ostream that writes to a file descriptor.
 ///
-class raw_fd_ostream : public raw_pwrite_stream {
+class LLVM_SUPPORT_ABI raw_fd_ostream : public raw_pwrite_stream {
   int FD;
   bool ShouldClose;
   bool SupportsSeeking = false;
@@ -574,17 +576,17 @@
 
 /// This returns a reference to a raw_fd_ostream for standard output. Use it
 /// like: outs() << "foo" << "bar";
-raw_fd_ostream &outs();
+LLVM_SUPPORT_ABI raw_fd_ostream &outs();
 
 /// This returns a reference to a raw_ostream for standard error.
 /// Use it like: errs() << "foo" << "bar";
 /// By default, the stream is tied to stdout to ensure stdout is flushed before
 /// stderr is written, to ensure the error messages are written in their
 /// expected place.
-raw_fd_ostream &errs();
+LLVM_SUPPORT_ABI raw_fd_ostream &errs();
 
 /// This returns a reference to a raw_ostream which simply discards output.
-raw_ostream &nulls();
+LLVM_SUPPORT_ABI raw_ostream &nulls();
 
 //===----------------------------------------------------------------------===//
 // File Streams
@@ -620,7 +622,7 @@
 
 /// A raw_ostream that writes to an std::string.  This is a simple adaptor
 /// class. This class does not encounter output errors.
-class raw_string_ostream : public raw_ostream {
+class LLVM_SUPPORT_ABI raw_string_ostream : public raw_ostream {
   std::string &OS;
 
   /// See raw_ostream::write_impl.
@@ -653,7 +655,7 @@
 /// raw_svector_ostream operates without a buffer, delegating all memory
 /// management to the SmallString. Thus the SmallString is always up-to-date,
 /// may be used directly and there is no need to call flush().
-class raw_svector_ostream : public raw_pwrite_stream {
+class LLVM_SUPPORT_ABI raw_svector_ostream : public raw_pwrite_stream {
   SmallVectorImpl<char> &OS;
 
   /// See raw_ostream::write_impl.
@@ -686,7 +688,7 @@
 };
 
 /// A raw_ostream that discards all output.
-class raw_null_ostream : public raw_pwrite_stream {
+class LLVM_SUPPORT_ABI raw_null_ostream : public raw_pwrite_stream {
   /// See raw_ostream::write_impl.
   void write_impl(const char *Ptr, size_t size) override;
   void pwrite_impl(const char *Ptr, size_t Size, uint64_t Offset) override;
diff --git a/llvm/lib/Support/CMakeLists.txt b/llvm/lib/Support/CMakeLists.txt
--- a/llvm/lib/Support/CMakeLists.txt
+++ b/llvm/lib/Support/CMakeLists.txt
@@ -101,7 +101,7 @@
   endif()
 endif()
 
-add_llvm_component_library(LLVMSupport
+add_llvm_component_library(LLVMSupport SHARED
   AArch64TargetParser.cpp
   ABIBreak.cpp
   ARMTargetParser.cpp
@@ -281,7 +281,12 @@
   set(llvm_system_libs ${llvm_system_libs} "${terminfo_library}")
 endif()
 
-set_property(TARGET LLVMSupport PROPERTY LLVM_SYSTEM_LIBS "${llvm_system_libs}")
+set_target_properties(LLVMSupport PROPERTIES
+  LLVM_SYSTEM_LIBS "${llvm_system_libs}"
+  DEFINE_SYMBOL "LLVMSupport_EXPORTS"
+  C_VISIBILITY_PRESET hidden
+  CXX_VISIBILITY_PRESET hidden
+  VISIBILITY_INLINES_HIDDEN YES)
 
 
 if(LLVM_INTEGRATED_CRT_ALLOC)