diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h
--- a/clang/include/clang/AST/Decl.h
+++ b/clang/include/clang/AST/Decl.h
@@ -4650,6 +4650,51 @@
   static bool classofKind(Kind K) { return K == Empty; }
 };
 
+/// HLSLBufferDecl - Represent a cbuffer or tbuffer declaration.
+class HLSLBufferDecl : public NamedDecl, public DeclContext {
+  /// LBraceLoc - The ending location of the source range.
+  SourceLocation LBraceLoc;
+  /// RBraceLoc - The ending location of the source range.
+  SourceLocation RBraceLoc;
+  /// KwLoc - The location of the cbuffer or tbuffer keyword.
+  SourceLocation KwLoc;
+  /// IsCBuffer - Whether the buffer is a cbuffer (and not a tbuffer).
+  bool IsCBuffer;
+
+  HLSLBufferDecl(DeclContext *DC, bool CBuffer, SourceLocation KwLoc,
+                 IdentifierInfo *ID, SourceLocation IDLoc,
+                 SourceLocation LBrace);
+
+public:
+  static HLSLBufferDecl *Create(ASTContext &C, DeclContext *LexicalParent,
+                                bool CBuffer, SourceLocation KwLoc,
+                                IdentifierInfo *ID, SourceLocation IDLoc,
+                                SourceLocation LBrace);
+  static HLSLBufferDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+
+  virtual SourceRange getSourceRange() const LLVM_READONLY {
+    return SourceRange(getLocStart(), RBraceLoc);
+  }
+  const char *getDeclKindName() const;
+  SourceLocation getLocStart() const LLVM_READONLY { return KwLoc; }
+  SourceLocation getRBraceLoc() const { return RBraceLoc; }
+  void setRBraceLoc(SourceLocation L) { RBraceLoc = L; }
+  bool isCBuffer() const { return IsCBuffer; }
+
+  // Implement isa/cast/dyncast/etc.
+  static bool classof(const Decl *D) { return classofKind(D->getKind()); }
+  static bool classofKind(Kind K) { return K == HLSLBuffer; }
+  static DeclContext *castToDeclContext(const HLSLBufferDecl *D) {
+    return static_cast<DeclContext *>(const_cast<HLSLBufferDecl *>(D));
+  }
+  static HLSLBufferDecl *castFromDeclContext(const DeclContext *DC) {
+    return static_cast<HLSLBufferDecl *>(const_cast<DeclContext *>(DC));
+  }
+
+  friend class ASTDeclReader;
+  friend class ASTDeclWriter;
+};
+
 /// Insertion operator for diagnostics.  This allows sending NamedDecl's
 /// into a diagnostic with <<.
 inline const StreamingDiagnostic &operator<<(const StreamingDiagnostic &PD,
diff --git a/clang/include/clang/AST/RecursiveASTVisitor.h b/clang/include/clang/AST/RecursiveASTVisitor.h
--- a/clang/include/clang/AST/RecursiveASTVisitor.h
+++ b/clang/include/clang/AST/RecursiveASTVisitor.h
@@ -1551,6 +1551,8 @@
 
 DEF_TRAVERSE_DECL(EmptyDecl, {})
 
+DEF_TRAVERSE_DECL(HLSLBufferDecl, {})
+
 DEF_TRAVERSE_DECL(LifetimeExtendedTemporaryDecl, {
   TRY_TO(TraverseStmt(D->getTemporaryExpr()));
 })
diff --git a/clang/include/clang/AST/TextNodeDumper.h b/clang/include/clang/AST/TextNodeDumper.h
--- a/clang/include/clang/AST/TextNodeDumper.h
+++ b/clang/include/clang/AST/TextNodeDumper.h
@@ -380,6 +380,7 @@
   void VisitConceptDecl(const ConceptDecl *D);
   void
   VisitLifetimeExtendedTemporaryDecl(const LifetimeExtendedTemporaryDecl *D);
+  void VisitHLSLBufferDecl(const HLSLBufferDecl *D);
 };
 
 } // namespace clang
diff --git a/clang/include/clang/Basic/DeclNodes.td b/clang/include/clang/Basic/DeclNodes.td
--- a/clang/include/clang/Basic/DeclNodes.td
+++ b/clang/include/clang/Basic/DeclNodes.td
@@ -108,4 +108,4 @@
 def Empty : DeclNode<Decl>;
 def RequiresExprBody : DeclNode<Decl>, DeclContext;
 def LifetimeExtendedTemporary : DeclNode<Decl>;
-
+def HLSLBuffer : DeclNode<Named, "HLSLBuffer">, DeclContext;
diff --git a/clang/include/clang/Basic/TokenKinds.def b/clang/include/clang/Basic/TokenKinds.def
--- a/clang/include/clang/Basic/TokenKinds.def
+++ b/clang/include/clang/Basic/TokenKinds.def
@@ -602,6 +602,10 @@
 // CUDA/HIP function attributes
 KEYWORD(__noinline__                , KEYCUDA)
 
+// HLSL keywords.
+KEYWORD(cbuffer                     , KEYHLSL)
+KEYWORD(tbuffer                     , KEYHLSL)
+
 // OpenMP Type Traits
 UNARY_EXPR_OR_TYPE_TRAIT(__builtin_omp_required_simd_align, OpenMPRequiredSimdAlign, KEYALL)
 
diff --git a/clang/include/clang/Parse/Parser.h b/clang/include/clang/Parse/Parser.h
--- a/clang/include/clang/Parse/Parser.h
+++ b/clang/include/clang/Parse/Parser.h
@@ -2817,6 +2817,8 @@
 
   void ParseHLSLSemantics(ParsedAttributes &Attrs,
                           SourceLocation *EndLoc = nullptr);
+  Decl *ParseHLSLBuffer(SourceLocation &DeclEnd,
+                        SourceLocation InlineLoc = SourceLocation());
 
   void MaybeParseMicrosoftAttributes(ParsedAttributes &Attrs) {
     if ((getLangOpts().MicrosoftExt || getLangOpts().HLSL) &&
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -5913,6 +5913,12 @@
                              SourceLocation BuiltinLoc,
                              SourceLocation RParenLoc);
 
+  //===---------------------------- HLSL Features -------------------------===//
+  Decl *ActOnStartHLSLBuffer(Scope *BufferScope, bool CBuffer,
+                             SourceLocation KwLoc, IdentifierInfo *Ident,
+                             SourceLocation IdentLoc, SourceLocation LBrace);
+  void ActOnFinishHLSLBuffer(Decl *Dcl, SourceLocation RBrace);
+
   //===---------------------------- C++ Features --------------------------===//
 
   // Act on C++ namespaces
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -5169,6 +5169,33 @@
   return new (C, ID) EmptyDecl(nullptr, SourceLocation());
 }
 
+HLSLBufferDecl::HLSLBufferDecl(DeclContext *DC, bool CBuffer,
+                               SourceLocation KwLoc, IdentifierInfo *ID,
+                               SourceLocation IDLoc, SourceLocation LBrace)
+    : NamedDecl(Decl::Kind::HLSLBuffer, DC, IDLoc, DeclarationName(ID)),
+      DeclContext(Decl::Kind::HLSLBuffer), LBraceLoc(LBrace), KwLoc(KwLoc),
+      IsCBuffer(CBuffer) {}
+
+HLSLBufferDecl *HLSLBufferDecl::Create(ASTContext &C,
+                                       DeclContext *LexicalParent, bool CBuffer,
+                                       SourceLocation KwLoc, IdentifierInfo *ID,
+                                       SourceLocation IDLoc,
+                                       SourceLocation LBrace) {
+  DeclContext *DC = C.getTranslationUnitDecl();
+  HLSLBufferDecl *Result =
+      new (C, DC) HLSLBufferDecl(DC, CBuffer, KwLoc, ID, IDLoc, LBrace);
+  if (DC != LexicalParent) {
+    Result->setLexicalDeclContext(LexicalParent);
+  }
+
+  return Result;
+}
+
+HLSLBufferDecl *HLSLBufferDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
+  return new (C, ID) HLSLBufferDecl(nullptr, false, SourceLocation(), nullptr,
+                                    SourceLocation(), SourceLocation());
+}
+
 //===----------------------------------------------------------------------===//
 // ImportDecl Implementation
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -749,6 +749,7 @@
     case ObjCMethod:
     case ObjCProperty:
     case MSProperty:
+    case HLSLBuffer:
       return IDNS_Ordinary;
     case Label:
       return IDNS_Label;
@@ -1187,6 +1188,9 @@
   if (getDeclKind() == Decl::Enum)
     return !cast<EnumDecl>(this)->isScoped();
 
+  if (getDeclKind() == Decl::HLSLBuffer)
+    return true;
+
   return getDeclKind() == Decl::LinkageSpec || getDeclKind() == Decl::Export;
 }
 
@@ -1252,6 +1256,10 @@
     // There is only one DeclContext for these entities.
     return this;
 
+  case Decl::HLSLBuffer:
+    // Each buffer, even with the same name, is a distinct construct.
+    return this;
+
   case Decl::TranslationUnit:
     return static_cast<TranslationUnitDecl *>(this)->getFirstDecl();
   case Decl::Namespace:
diff --git a/clang/lib/AST/DeclPrinter.cpp b/clang/lib/AST/DeclPrinter.cpp
--- a/clang/lib/AST/DeclPrinter.cpp
+++ b/clang/lib/AST/DeclPrinter.cpp
@@ -108,6 +108,7 @@
     void VisitOMPCapturedExprDecl(OMPCapturedExprDecl *D);
     void VisitTemplateTypeParmDecl(const TemplateTypeParmDecl *TTP);
     void VisitNonTypeTemplateParmDecl(const NonTypeTemplateParmDecl *NTTP);
+    void VisitHLSLBufferDecl(HLSLBufferDecl *D);
 
     void printTemplateParameters(const TemplateParameterList *Params,
                                  bool OmitTemplateKW = false);
@@ -467,7 +468,8 @@
              isa<ObjCInterfaceDecl>(*D) ||
              isa<ObjCProtocolDecl>(*D) ||
              isa<ObjCCategoryImplDecl>(*D) ||
-             isa<ObjCCategoryDecl>(*D))
+             isa<ObjCCategoryDecl>(*D) ||
+             isa<HLSLBufferDecl>(*D))
       Terminator = nullptr;
     else if (isa<EnumConstantDecl>(*D)) {
       DeclContext::decl_iterator Next = D;
@@ -1658,6 +1660,22 @@
   }
 }
 
+void DeclPrinter::VisitHLSLBufferDecl(HLSLBufferDecl *D) {
+  if (D->isCBuffer()) {
+    Out << "cbuffer ";
+  } else {
+    Out << "tbuffer ";
+  }
+
+  Out << *D;
+
+  prettyPrintAttributes(D);
+
+  Out << " {\n";
+  VisitDeclContext(D);
+  Indent() << "}";
+}
+
 void DeclPrinter::VisitOMPAllocateDecl(OMPAllocateDecl *D) {
   Out << "#pragma omp allocate";
   if (!D->varlist_empty()) {
diff --git a/clang/lib/AST/TextNodeDumper.cpp b/clang/lib/AST/TextNodeDumper.cpp
--- a/clang/lib/AST/TextNodeDumper.cpp
+++ b/clang/lib/AST/TextNodeDumper.cpp
@@ -2377,3 +2377,11 @@
   if (S->hasStoredFPFeatures())
     printFPOptions(S->getStoredFPFeatures());
 }
+
+void TextNodeDumper::VisitHLSLBufferDecl(const HLSLBufferDecl *D) {
+  if (D->isCBuffer())
+    OS << " cbuffer";
+  else
+    OS << " tbuffer";
+  dumpName(D);
+}
diff --git a/clang/lib/Basic/IdentifierTable.cpp b/clang/lib/Basic/IdentifierTable.cpp
--- a/clang/lib/Basic/IdentifierTable.cpp
+++ b/clang/lib/Basic/IdentifierTable.cpp
@@ -109,7 +109,8 @@
     KEYMSCOMPAT   = 0x800000,
     KEYSYCL       = 0x1000000,
     KEYCUDA       = 0x2000000,
-    KEYMAX        = KEYCUDA, // The maximum key
+    KEYHLSL       = 0x4000000,
+    KEYMAX        = KEYHLSL, // The maximum key
     KEYALLCXX = KEYCXX | KEYCXX11 | KEYCXX20,
     KEYALL = (KEYMAX | (KEYMAX-1)) & ~KEYNOMS18 &
              ~KEYNOOPENCL // KEYNOMS18 and KEYNOOPENCL are used to exclude.
@@ -162,6 +163,8 @@
     return KS_Enabled;
   if (LangOpts.CUDA && (Flags & KEYCUDA))
     return KS_Enabled;
+  if (LangOpts.HLSL && (Flags & KEYHLSL))
+    return KS_Enabled;
   return KS_Disabled;
 }
 
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -1787,6 +1787,11 @@
     }
     return ParseSimpleDeclaration(Context, DeclEnd, DeclAttrs, DeclSpecAttrs,
                                   true, nullptr, DeclSpecStart);
+
+  case tok::kw_cbuffer:
+  case tok::kw_tbuffer:
+    SingleDecl = ParseHLSLBuffer(DeclEnd);
+    break;
   case tok::kw_namespace:
     ProhibitAttributes(DeclAttrs);
     ProhibitAttributes(DeclSpecAttrs);
diff --git a/clang/lib/Parse/ParseHLSL.cpp b/clang/lib/Parse/ParseHLSL.cpp
--- a/clang/lib/Parse/ParseHLSL.cpp
+++ b/clang/lib/Parse/ParseHLSL.cpp
@@ -13,9 +13,52 @@
 #include "clang/Basic/AttributeCommonInfo.h"
 #include "clang/Parse/ParseDiagnostic.h"
 #include "clang/Parse/Parser.h"
+#include "clang/Parse/RAIIObjectsForParser.h"
 
 using namespace clang;
 
+Decl *Parser::ParseHLSLBuffer(SourceLocation &DeclEnd,
+                              SourceLocation InlineLoc) {
+  assert((Tok.is(tok::kw_cbuffer) || Tok.is(tok::kw_tbuffer)) &&
+         "Not a cbuffer or tbuffer!");
+  bool IsCBuffer = Tok.is(tok::kw_cbuffer);
+  SourceLocation BufferLoc = ConsumeToken(); // eat the 'cbuffer or tbuffer'.
+
+  if (!Tok.is(tok::identifier)) {
+    Diag(Tok, diag::err_expected) << tok::identifier;
+    return nullptr;
+  }
+
+  IdentifierInfo *Identifier = Tok.getIdentifierInfo();
+  SourceLocation IdentifierLoc = ConsumeToken(); // consume identifier
+
+  ParseScope BufferScope(this, Scope::DeclScope);
+  BalancedDelimiterTracker T(*this, tok::l_brace);
+  if (T.consumeOpen()) {
+    Diag(Tok, diag::err_expected) << tok::l_brace;
+    return nullptr;
+  }
+
+  Decl *D = Actions.ActOnStartHLSLBuffer(getCurScope(), IsCBuffer, BufferLoc,
+                                         Identifier, IdentifierLoc,
+                                         T.getOpenLocation());
+
+  // FIXME: support attribute on cbuffer/tbuffer.
+
+  while (Tok.isNot(tok::r_brace) && Tok.isNot(tok::eof)) {
+    ParsedAttributes Attrs(AttrFactory);
+    // FIXME: support attribute on constants inside cbuffer/tbuffer.
+    ParseExternalDeclaration(Attrs);
+  }
+
+  T.consumeClose();
+  DeclEnd = T.getCloseLocation();
+  BufferScope.Exit();
+  Actions.ActOnFinishHLSLBuffer(D, DeclEnd);
+
+  return D;
+}
+
 void Parser::ParseHLSLSemantics(ParsedAttributes &Attrs,
                                 SourceLocation *EndLoc) {
   assert(Tok.is(tok::colon) && "Not a HLSL Semantic");
diff --git a/clang/lib/Parse/Parser.cpp b/clang/lib/Parse/Parser.cpp
--- a/clang/lib/Parse/Parser.cpp
+++ b/clang/lib/Parse/Parser.cpp
@@ -947,6 +947,16 @@
                               EmptyDeclSpecAttrs);
     }
 
+  case tok::kw_cbuffer:
+  case tok::kw_tbuffer:
+    if (getLangOpts().HLSL) {
+      SourceLocation DeclEnd;
+      ParsedAttributes EmptyDeclSpecAttrs(AttrFactory);
+      return ParseDeclaration(DeclaratorContext::File, DeclEnd, Attrs,
+                              EmptyDeclSpecAttrs);
+    }
+    goto dont_know;
+
   case tok::kw_static:
     // Parse (then ignore) 'static' prior to a template instantiation. This is
     // a GCC extension that we intentionally do not support.
diff --git a/clang/lib/Sema/CMakeLists.txt b/clang/lib/Sema/CMakeLists.txt
--- a/clang/lib/Sema/CMakeLists.txt
+++ b/clang/lib/Sema/CMakeLists.txt
@@ -44,6 +44,7 @@
   SemaExprMember.cpp
   SemaExprObjC.cpp
   SemaFixItUtils.cpp
+  SemaHLSL.cpp
   SemaInit.cpp
   SemaLambda.cpp
   SemaLookup.cpp
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -7039,6 +7039,9 @@
     return true;
   if (DC->isRecord())
     return false;
+  if (DC->getDeclKind() == Decl::HLSLBuffer)
+    return false;
+
   if (isa<RequiresExprBodyDecl>(DC))
     return false;
   llvm_unreachable("Unexpected context");
diff --git a/clang/lib/Sema/SemaHLSL.cpp b/clang/lib/Sema/SemaHLSL.cpp
new file mode 100644
--- /dev/null
+++ b/clang/lib/Sema/SemaHLSL.cpp
@@ -0,0 +1,37 @@
+//===- SemaHLSL.cpp - Semantic Analysis for HLSL constructs ---------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+// This implements Semantic Analysis for HLSL constructs.
+//===----------------------------------------------------------------------===//
+
+#include "clang/Sema/Sema.h"
+
+using namespace clang;
+
+Decl *Sema::ActOnStartHLSLBuffer(Scope *BufferScope, bool CBuffer,
+                                 SourceLocation KwLoc, IdentifierInfo *Ident,
+                                 SourceLocation IdentLoc,
+                                 SourceLocation LBrace) {
+  // For anonymous namespace, take the location of the left brace.
+  DeclContext *LexicalParent = getCurLexicalContext();
+  HLSLBufferDecl *Result = HLSLBufferDecl::Create(
+      Context, LexicalParent, CBuffer, KwLoc, Ident, IdentLoc, LBrace);
+
+  PushOnScopeChains(Result, BufferScope);
+  PushDeclContext(BufferScope, Result);
+
+  ActOnDocumentableDecl(Result);
+
+  return Result;
+}
+
+void Sema::ActOnFinishHLSLBuffer(Decl *Dcl, SourceLocation RBrace) {
+  HLSLBufferDecl *BufDecl = dyn_cast_or_null<HLSLBufferDecl>(Dcl);
+  assert(BufDecl && "Invalid parameter, expected HLSLBufferDecl");
+  BufDecl->setRBraceLoc(RBrace);
+  PopDeclContext();
+}
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -873,6 +873,10 @@
   llvm_unreachable("Translation units cannot be instantiated");
 }
 
+Decl *TemplateDeclInstantiator::VisitHLSLBufferDecl(HLSLBufferDecl *Decl) {
+  llvm_unreachable("HLSL buffer declarations cannot be instantiated");
+}
+
 Decl *
 TemplateDeclInstantiator::VisitPragmaCommentDecl(PragmaCommentDecl *D) {
   llvm_unreachable("pragma comment cannot be instantiated");
diff --git a/clang/lib/Serialization/ASTCommon.cpp b/clang/lib/Serialization/ASTCommon.cpp
--- a/clang/lib/Serialization/ASTCommon.cpp
+++ b/clang/lib/Serialization/ASTCommon.cpp
@@ -433,6 +433,7 @@
   case Decl::LifetimeExtendedTemporary:
   case Decl::RequiresExprBody:
   case Decl::UnresolvedUsingIfExists:
+  case Decl::HLSLBuffer:
     return false;
 
   // These indirectly derive from Redeclarable<T> but are not actually
diff --git a/clang/test/AST/HLSL/cbuffer_tbuffer.hlsl b/clang/test/AST/HLSL/cbuffer_tbuffer.hlsl
new file mode 100644
--- /dev/null
+++ b/clang/test/AST/HLSL/cbuffer_tbuffer.hlsl
@@ -0,0 +1,22 @@
+// RUN: %clang_cc1 -triple dxil-pc-shadermodel6.3-library -x hlsl -ast-dump -o - %s | FileCheck %s
+
+// CHECK:HLSLBufferDecl 0x[[CB:[0-9a-f]+]] {{.*}} line:5:9 cbuffer CB
+// CHECK-NEXT:VarDecl 0x[[A:[0-9a-f]+]] {{.*}} col:9 used a 'float'
+cbuffer CB {
+  float a;
+}
+
+// CHECK:HLSLBufferDecl 0x[[TB:[0-9a-f]+]] {{.*}} line:11:9 tbuffer TB
+// CHECK-NEXT:VarDecl 0x[[B:[0-9a-f]+]] {{.*}} col:9 used b 'float'
+tbuffer TB {
+  float b;
+}
+
+float foo() {
+// CHECK: BinaryOperator 0x{{[0-9a-f]+}} <col:10, col:14> 'float' '+'
+// CHECK-NEXT: ImplicitCastExpr 0x{{[0-9a-f]+}} <col:10> 'float' <LValueToRValue>
+// CHECK-NEXT: DeclRefExpr 0x{{[0-9a-f]+}} <col:10> 'float' lvalue Var 0x[[A]] 'a' 'float'
+// CHECK-NEXT: ImplicitCastExpr 0x{{[0-9a-f]+}} <col:14> 'float' <LValueToRValue>
+// CHECK-NEXT: DeclRefExpr 0x{{[0-9a-f]+}} <col:14> 'float' lvalue Var 0x[[B]] 'b' 'float'
+  return a + b;
+}
diff --git a/clang/test/SemaHLSL/cb_error.hlsl b/clang/test/SemaHLSL/cb_error.hlsl
new file mode 100644
--- /dev/null
+++ b/clang/test/SemaHLSL/cb_error.hlsl
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -triple dxil-pc-shadermodel6.3-library -x hlsl -o - -fsyntax-only %s -verify
+
+// expected-error@+2 {{expected identifier}}
+// expected-error@+1 {{expected unqualified-id}}
+cbuffer { ... };
+// expected-error@+1 {{expected '{'}}
+cbuffer missing_definition;
+// expected-error@+1 {{expected unqualified-id}}
+int cbuffer;
+// expected-error@+1 {{expected identifier}}
+cbuffer;
+