diff --git a/llvm/include/llvm/Support/HashBuilder.h b/llvm/include/llvm/Support/HashBuilder.h
--- a/llvm/include/llvm/Support/HashBuilder.h
+++ b/llvm/include/llvm/Support/HashBuilder.h
@@ -16,6 +16,7 @@
 #define LLVM_SUPPORT_HASHBUILDER_H
 
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Endian.h"
@@ -26,6 +27,15 @@
 
 namespace llvm {
 
+namespace hashbuilder_detail {
+/// Trait to indicate whether a type's bits can be hashed directly (after
+/// endianness correction).
+template <typename U>
+struct IsHashableData
+    : std::integral_constant<bool, is_integral_or_enum<U>::value> {};
+
+} // namespace hashbuilder_detail
+
 /// Declares the hasher member, and functions forwarding directly to the hasher.
 template <typename HasherT> class HashBuilderBase {
 public:
@@ -78,15 +88,10 @@
 /// `support::endianness::big` or `support::endianness::little`.
 template <typename HasherT, support::endianness Endianness>
 class HashBuilderImpl : public HashBuilderBase<HasherT> {
+public:
   static_assert(Endianness != support::endianness::native,
                 "HashBuilder should canonicalize endianness");
-  /// Trait to indicate whether a type's bits can be hashed directly (after
-  /// endianness correction).
-  template <typename U>
-  struct IsHashableData
-      : std::integral_constant<bool, is_integral_or_enum<U>::value> {};
 
-public:
   explicit HashBuilderImpl(HasherT &Hasher)
       : HashBuilderBase<HasherT>(Hasher) {}
   template <typename... ArgTypes>
@@ -95,7 +100,9 @@
 
   /// Implement hashing for hashable data types, e.g. integral or enum values.
   template <typename T>
-  std::enable_if_t<IsHashableData<T>::value, HashBuilderImpl &> add(T Value) {
+  std::enable_if_t<hashbuilder_detail::IsHashableData<T>::value,
+                   HashBuilderImpl &>
+  add(T Value) {
     return adjustForEndiannessAndAdd(Value);
   }
 
@@ -118,7 +125,7 @@
     // details of `ArrayRef::begin()` and `ArrayRef::end()`. Explicitly call
     // `update` to guarantee the fast path.
     add(Value.size());
-    if (IsHashableData<T>::value &&
+    if (hashbuilder_detail::IsHashableData<T>::value &&
         Endianness == support::endian::system_endianness()) {
       this->update(
           makeArrayRef(reinterpret_cast<const uint8_t *>(Value.begin()),
@@ -242,7 +249,7 @@
   /// ```
   template <typename T>
   std::enable_if_t<is_detected<HasAddHashT, T>::value &&
-                       !IsHashableData<T>::value,
+                       !hashbuilder_detail::IsHashableData<T>::value,
                    HashBuilderImpl &>
   add(const T &Value) {
     addHash(*this, Value);
@@ -334,7 +341,7 @@
   }
 
   template <typename T>
-  std::enable_if_t<IsHashableData<T>::value &&
+  std::enable_if_t<hashbuilder_detail::IsHashableData<T>::value &&
                        Endianness == support::endian::system_endianness(),
                    HashBuilderImpl &>
   addRangeElementsImpl(T *First, T *Last, std::forward_iterator_tag) {
@@ -399,6 +406,33 @@
     HashBuilderImpl<HasherT, (Endianness == support::endianness::native
                                   ? support::endian::system_endianness()
                                   : Endianness)>;
+
+class HashCodeHasher {
+public:
+  HashCodeHasher() : Code(0) {}
+  void update(ArrayRef<uint8_t> Data) {
+    hash_code DataCode = hash_value(Data);
+    Code = hash_combine(Code, DataCode);
+  }
+  hash_code Code;
+};
+
+namespace hashbuilder_detail {
+/// Provide a default implementation of `hash_value` when `addHash(const T &)`
+/// is supported.
+using HashCodeHashBuilder =
+    HashBuilder<HashCodeHasher, support::endianness::native>;
+} // namespace hashbuilder_detail
+
+template <typename T>
+std::enable_if_t<
+    is_detected<hashbuilder_detail::HashCodeHashBuilder::HasAddHashT, T>::value,
+    hash_code>
+hash_value(const T &Value) {
+  hashbuilder_detail::HashCodeHashBuilder HBuilder;
+  HBuilder.add(Value);
+  return HBuilder.getHasher().Code;
+}
 } // end namespace llvm
 
 #endif // LLVM_SUPPORT_HASHBUILDER_H
diff --git a/llvm/unittests/ADT/HashingTest.cpp b/llvm/unittests/ADT/HashingTest.cpp
--- a/llvm/unittests/ADT/HashingTest.cpp
+++ b/llvm/unittests/ADT/HashingTest.cpp
@@ -12,6 +12,7 @@
 
 #include "llvm/ADT/Hashing.h"
 #include "llvm/Support/DataTypes.h"
+#include "llvm/Support/HashBuilder.h"
 #include "gtest/gtest.h"
 #include <deque>
 #include <list>
@@ -402,4 +403,36 @@
 #undef CHECK_SAME
 }
 
+struct StructWithHashBuilderSupport {
+  char C;
+  int I;
+  template <typename HasherT, llvm::support::endianness Endianness>
+  friend void addHash(llvm::HashBuilderImpl<HasherT, Endianness> &HBuilder,
+                      const StructWithHashBuilderSupport &Value) {
+    HBuilder.add(Value.C, Value.I);
+  }
+};
+
+TEST(HashingTest, HashWithHashBuilder) {
+  StructWithHashBuilderSupport S{'c', 1};
+  EXPECT_NE(static_cast<size_t>(llvm::hash_value(S)), static_cast<size_t>(0));
 }
+
+struct StructWithHashBuilderAndHashValueSupport {
+  char C;
+  int I;
+  template <typename HasherT, llvm::support::endianness Endianness>
+  friend void addHash(llvm::HashBuilderImpl<HasherT, Endianness> &HBuilder,
+                      const StructWithHashBuilderAndHashValueSupport &Value) {}
+  friend hash_code
+  hash_value(const StructWithHashBuilderAndHashValueSupport &Value) {
+    return 0xbeef;
+  }
+};
+
+TEST(HashingTest, HashBuilderAndHashValue) {
+  StructWithHashBuilderAndHashValueSupport S{'c', 1};
+  EXPECT_EQ(static_cast<size_t>(hash_value(S)), static_cast<size_t>(0xbeef));
+}
+
+} // namespace