diff --git a/llvm/include/llvm/ADT/ScopedHashTable.h b/llvm/include/llvm/ADT/ScopedHashTable.h
--- a/llvm/include/llvm/ADT/ScopedHashTable.h
+++ b/llvm/include/llvm/ADT/ScopedHashTable.h
@@ -32,7 +32,7 @@
 
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/DenseMapInfo.h"
-#include "llvm/Support/Allocator.h"
+#include "llvm/Support/AllocatorBase.h"
 #include <cassert>
 #include <new>
 
diff --git a/llvm/include/llvm/ADT/SparseSet.h b/llvm/include/llvm/ADT/SparseSet.h
--- a/llvm/include/llvm/ADT/SparseSet.h
+++ b/llvm/include/llvm/ADT/SparseSet.h
@@ -21,7 +21,7 @@
 
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
-#include "llvm/Support/Allocator.h"
+#include "llvm/Support/AllocatorBase.h"
 #include <cassert>
 #include <cstdint>
 #include <cstdlib>
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
@@ -16,9 +16,8 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/iterator.h"
 #include "llvm/ADT/iterator_range.h"
-#include "llvm/Support/Allocator.h"
+#include "llvm/Support/AllocatorBase.h"
 #include "llvm/Support/PointerLikeTypeTraits.h"
-#include "llvm/Support/ErrorHandling.h"
 #include <algorithm>
 #include <cassert>
 #include <cstdint>
diff --git a/llvm/include/llvm/ADT/StringSet.h b/llvm/include/llvm/ADT/StringSet.h
--- a/llvm/include/llvm/ADT/StringSet.h
+++ b/llvm/include/llvm/ADT/StringSet.h
@@ -15,7 +15,7 @@
 
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
-#include "llvm/Support/Allocator.h"
+#include "llvm/Support/AllocatorBase.h"
 #include <cassert>
 #include <initializer_list>
 #include <utility>
diff --git a/llvm/include/llvm/BinaryFormat/MachO.h b/llvm/include/llvm/BinaryFormat/MachO.h
--- a/llvm/include/llvm/BinaryFormat/MachO.h
+++ b/llvm/include/llvm/BinaryFormat/MachO.h
@@ -15,7 +15,7 @@
 
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/DataTypes.h"
-#include "llvm/Support/Host.h"
+#include "llvm/Support/SwapByteOrder.h"
 
 namespace llvm {
 namespace MachO {
diff --git a/llvm/include/llvm/DebugInfo/CodeView/ContinuationRecordBuilder.h b/llvm/include/llvm/DebugInfo/CodeView/ContinuationRecordBuilder.h
--- a/llvm/include/llvm/DebugInfo/CodeView/ContinuationRecordBuilder.h
+++ b/llvm/include/llvm/DebugInfo/CodeView/ContinuationRecordBuilder.h
@@ -18,7 +18,6 @@
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
 #include "llvm/DebugInfo/CodeView/TypeRecordMapping.h"
 #include "llvm/DebugInfo/CodeView/TypeVisitorCallbacks.h"
-#include "llvm/Support/Allocator.h"
 #include "llvm/Support/BinaryByteStream.h"
 #include "llvm/Support/BinaryStreamWriter.h"
 #include "llvm/Support/Error.h"
diff --git a/llvm/include/llvm/DebugInfo/PDB/Native/SymbolCache.h b/llvm/include/llvm/DebugInfo/PDB/Native/SymbolCache.h
--- a/llvm/include/llvm/DebugInfo/PDB/Native/SymbolCache.h
+++ b/llvm/include/llvm/DebugInfo/PDB/Native/SymbolCache.h
@@ -14,7 +14,6 @@
 #include "llvm/DebugInfo/CodeView/TypeIndex.h"
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
 #include "llvm/DebugInfo/PDB/Native/NativeRawSymbol.h"
-#include "llvm/Support/Allocator.h"
 
 #include <memory>
 #include <vector>
diff --git a/llvm/include/llvm/Object/IRSymtab.h b/llvm/include/llvm/Object/IRSymtab.h
--- a/llvm/include/llvm/Object/IRSymtab.h
+++ b/llvm/include/llvm/Object/IRSymtab.h
@@ -28,6 +28,7 @@
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/IR/GlobalValue.h"
 #include "llvm/Object/SymbolicFile.h"
+#include "llvm/Support/Allocator.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 #include <cassert>
diff --git a/llvm/include/llvm/ProfileData/SampleProf.h b/llvm/include/llvm/ProfileData/SampleProf.h
--- a/llvm/include/llvm/ProfileData/SampleProf.h
+++ b/llvm/include/llvm/ProfileData/SampleProf.h
@@ -22,6 +22,7 @@
 #include "llvm/IR/Function.h"
 #include "llvm/IR/GlobalValue.h"
 #include "llvm/IR/Module.h"
+#include "llvm/Support/Allocator.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorOr.h"
 #include "llvm/Support/MathExtras.h"
diff --git a/llvm/include/llvm/Remarks/RemarkStringTable.h b/llvm/include/llvm/Remarks/RemarkStringTable.h
--- a/llvm/include/llvm/Remarks/RemarkStringTable.h
+++ b/llvm/include/llvm/Remarks/RemarkStringTable.h
@@ -19,6 +19,7 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Remarks/Remark.h"
+#include "llvm/Support/Allocator.h"
 #include <vector>
 
 namespace llvm {
diff --git a/llvm/include/llvm/Support/Allocator.h b/llvm/include/llvm/Support/Allocator.h
--- a/llvm/include/llvm/Support/Allocator.h
+++ b/llvm/include/llvm/Support/Allocator.h
@@ -23,6 +23,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/Alignment.h"
+#include "llvm/Support/AllocatorBase.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/MathExtras.h"
@@ -38,81 +39,6 @@
 
 namespace llvm {
 
-/// CRTP base class providing obvious overloads for the core \c
-/// Allocate() methods of LLVM-style allocators.
-///
-/// This base class both documents the full public interface exposed by all
-/// LLVM-style allocators, and redirects all of the overloads to a single core
-/// set of methods which the derived class must define.
-template <typename DerivedT> class AllocatorBase {
-public:
-  /// Allocate \a Size bytes of \a Alignment aligned memory. This method
-  /// must be implemented by \c DerivedT.
-  void *Allocate(size_t Size, size_t Alignment) {
-#ifdef __clang__
-    static_assert(static_cast<void *(AllocatorBase::*)(size_t, size_t)>(
-                      &AllocatorBase::Allocate) !=
-                      static_cast<void *(DerivedT::*)(size_t, size_t)>(
-                          &DerivedT::Allocate),
-                  "Class derives from AllocatorBase without implementing the "
-                  "core Allocate(size_t, size_t) overload!");
-#endif
-    return static_cast<DerivedT *>(this)->Allocate(Size, Alignment);
-  }
-
-  /// Deallocate \a Ptr to \a Size bytes of memory allocated by this
-  /// allocator.
-  void Deallocate(const void *Ptr, size_t Size) {
-#ifdef __clang__
-    static_assert(static_cast<void (AllocatorBase::*)(const void *, size_t)>(
-                      &AllocatorBase::Deallocate) !=
-                      static_cast<void (DerivedT::*)(const void *, size_t)>(
-                          &DerivedT::Deallocate),
-                  "Class derives from AllocatorBase without implementing the "
-                  "core Deallocate(void *) overload!");
-#endif
-    return static_cast<DerivedT *>(this)->Deallocate(Ptr, Size);
-  }
-
-  // The rest of these methods are helpers that redirect to one of the above
-  // core methods.
-
-  /// Allocate space for a sequence of objects without constructing them.
-  template <typename T> T *Allocate(size_t Num = 1) {
-    return static_cast<T *>(Allocate(Num * sizeof(T), alignof(T)));
-  }
-
-  /// Deallocate space for a sequence of objects without constructing them.
-  template <typename T>
-  typename std::enable_if<
-      !std::is_same<typename std::remove_cv<T>::type, void>::value, void>::type
-  Deallocate(T *Ptr, size_t Num = 1) {
-    Deallocate(static_cast<const void *>(Ptr), Num * sizeof(T));
-  }
-};
-
-class MallocAllocator : public AllocatorBase<MallocAllocator> {
-public:
-  void Reset() {}
-
-  LLVM_ATTRIBUTE_RETURNS_NONNULL void *Allocate(size_t Size,
-                                                size_t /*Alignment*/) {
-    return safe_malloc(Size);
-  }
-
-  // Pull in base class overloads.
-  using AllocatorBase<MallocAllocator>::Allocate;
-
-  void Deallocate(const void *Ptr, size_t /*Size*/) {
-    free(const_cast<void *>(Ptr));
-  }
-
-  // Pull in base class overloads.
-  using AllocatorBase<MallocAllocator>::Deallocate;
-
-  void PrintStats() const {}
-};
-
 namespace detail {
 
 // We call out to an external function to actually print the message as the
diff --git a/llvm/include/llvm/Support/AllocatorBase.h b/llvm/include/llvm/Support/AllocatorBase.h
new file mode 100644
--- /dev/null
+++ b/llvm/include/llvm/Support/AllocatorBase.h
@@ -0,0 +1,105 @@
+//===- AllocatorBase.h - Simple memory allocation abstraction -------*- 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 defines the MallocAllocator and BumpPtrAllocator interfaces. Both
+/// of these conform to an LLVM "Allocator" concept which consists of an
+/// Allocate method accepting a size and alignment, and a Deallocate accepting
+/// a pointer and size. Further, the LLVM "Allocator" concept has overloads of
+/// Allocate and Deallocate for setting size and alignment based on the final
+/// type. These overloads are typically provided by a base class template \c
+/// AllocatorBase.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_ALLOCATORBASE_H
+#define LLVM_SUPPORT_ALLOCATORBASE_H
+
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/MemAlloc.h"
+
+namespace llvm {
+
+/// CRTP base class providing obvious overloads for the core \c
+/// Allocate() methods of LLVM-style allocators.
+///
+/// This base class both documents the full public interface exposed by all
+/// LLVM-style allocators, and redirects all of the overloads to a single core
+/// set of methods which the derived class must define.
+template <typename DerivedT> class AllocatorBase {
+public:
+  /// Allocate \a Size bytes of \a Alignment aligned memory. This method
+  /// must be implemented by \c DerivedT.
+  void *Allocate(size_t Size, size_t Alignment) {
+#ifdef __clang__
+    static_assert(static_cast<void *(AllocatorBase::*)(size_t, size_t)>(
+                      &AllocatorBase::Allocate) !=
+                      static_cast<void *(DerivedT::*)(size_t, size_t)>(
+                          &DerivedT::Allocate),
+                  "Class derives from AllocatorBase without implementing the "
+                  "core Allocate(size_t, size_t) overload!");
+#endif
+    return static_cast<DerivedT *>(this)->Allocate(Size, Alignment);
+  }
+
+  /// Deallocate \a Ptr to \a Size bytes of memory allocated by this
+  /// allocator.
+  void Deallocate(const void *Ptr, size_t Size) {
+#ifdef __clang__
+    static_assert(static_cast<void (AllocatorBase::*)(const void *, size_t)>(
+                      &AllocatorBase::Deallocate) !=
+                      static_cast<void (DerivedT::*)(const void *, size_t)>(
+                          &DerivedT::Deallocate),
+                  "Class derives from AllocatorBase without implementing the "
+                  "core Deallocate(void *) overload!");
+#endif
+    return static_cast<DerivedT *>(this)->Deallocate(Ptr, Size);
+  }
+
+  // The rest of these methods are helpers that redirect to one of the above
+  // core methods.
+
+  /// Allocate space for a sequence of objects without constructing them.
+  template <typename T> T *Allocate(size_t Num = 1) {
+    return static_cast<T *>(Allocate(Num * sizeof(T), alignof(T)));
+  }
+
+  /// Deallocate space for a sequence of objects without constructing them.
+  template <typename T>
+  typename std::enable_if<
+      !std::is_same<typename std::remove_cv<T>::type, void>::value, void>::type
+  Deallocate(T *Ptr, size_t Num = 1) {
+    Deallocate(static_cast<const void *>(Ptr), Num * sizeof(T));
+  }
+};
+
+class MallocAllocator : public AllocatorBase<MallocAllocator> {
+public:
+  void Reset() {}
+
+  LLVM_ATTRIBUTE_RETURNS_NONNULL void *Allocate(size_t Size,
+                                                size_t /*Alignment*/) {
+    return safe_malloc(Size);
+  }
+
+  // Pull in base class overloads.
+  using AllocatorBase<MallocAllocator>::Allocate;
+
+  void Deallocate(const void *Ptr, size_t /*Size*/) {
+    free(const_cast<void *>(Ptr));
+  }
+
+  // Pull in base class overloads.
+  using AllocatorBase<MallocAllocator>::Deallocate;
+
+  void PrintStats() const {}
+};
+
+} // namespace llvm
+
+#endif // LLVM_SUPPORT_ALLOCATORBASE_H
diff --git a/llvm/include/llvm/Support/BinaryStreamReader.h b/llvm/include/llvm/Support/BinaryStreamReader.h
--- a/llvm/include/llvm/Support/BinaryStreamReader.h
+++ b/llvm/include/llvm/Support/BinaryStreamReader.h
@@ -11,6 +11,7 @@
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/Support/Alignment.h"
 #include "llvm/Support/BinaryStreamArray.h"
 #include "llvm/Support/BinaryStreamRef.h"
 #include "llvm/Support/ConvertUTF.h"
diff --git a/llvm/include/llvm/Support/Process.h b/llvm/include/llvm/Support/Process.h
--- a/llvm/include/llvm/Support/Process.h
+++ b/llvm/include/llvm/Support/Process.h
@@ -25,7 +25,7 @@
 #define LLVM_SUPPORT_PROCESS_H
 
 #include "llvm/ADT/Optional.h"
-#include "llvm/Support/Allocator.h"
+#include "llvm/Support/AllocatorBase.h"
 #include "llvm/Support/Chrono.h"
 #include "llvm/Support/DataTypes.h"
 #include "llvm/Support/Error.h"
diff --git a/llvm/lib/IR/SafepointIRVerifier.cpp b/llvm/lib/IR/SafepointIRVerifier.cpp
--- a/llvm/lib/IR/SafepointIRVerifier.cpp
+++ b/llvm/lib/IR/SafepointIRVerifier.cpp
@@ -45,6 +45,7 @@
 #include "llvm/IR/Statepoint.h"
 #include "llvm/IR/Value.h"
 #include "llvm/InitializePasses.h"
+#include "llvm/Support/Allocator.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
diff --git a/llvm/unittests/Support/BinaryStreamTest.cpp b/llvm/unittests/Support/BinaryStreamTest.cpp
--- a/llvm/unittests/Support/BinaryStreamTest.cpp
+++ b/llvm/unittests/Support/BinaryStreamTest.cpp
@@ -6,6 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Support/Allocator.h"
 #include "llvm/Support/BinaryByteStream.h"
 #include "llvm/Support/BinaryItemStream.h"
 #include "llvm/Support/BinaryStreamArray.h"