diff --git a/clang/include/clang/AST/StmtOpenMP.h b/clang/include/clang/AST/StmtOpenMP.h
--- a/clang/include/clang/AST/StmtOpenMP.h
+++ b/clang/include/clang/AST/StmtOpenMP.h
@@ -2842,6 +2842,8 @@
   /// This field is true for the first(postfix) form of the expression and false
   /// otherwise.
   bool IsPostfixUpdate = false;
+  ///
+  bool IsSignedOp = true;
 
   /// Build directive with the given start and end location.
   ///
@@ -2863,6 +2865,8 @@
     POS_V,
     POS_E,
     POS_UpdateExpr,
+    POS_D,
+    POS_Cond,
   };
 
   /// Set 'x' part of the associated expression/statement.
@@ -2877,6 +2881,10 @@
   void setV(Expr *V) { Data->getChildren()[DataPositionTy::POS_V] = V; }
   /// Set 'expr' part of the associated expression/statement.
   void setExpr(Expr *E) { Data->getChildren()[DataPositionTy::POS_E] = E; }
+  /// Set 'd' part of the associated expression/statement.
+  void setD(Expr *D) { Data->getChildren()[DataPositionTy::POS_D] = D; }
+  /// Set conditional expression in `atomic compare`.
+  void setCond(Expr *C) { Data->getChildren()[DataPositionTy::POS_Cond] = C; }
 
 public:
   /// Creates directive with a list of \a Clauses and 'x', 'v' and 'expr'
@@ -2894,14 +2902,18 @@
   /// \param UE Helper expression of the form
   /// 'OpaqueValueExpr(x) binop OpaqueValueExpr(expr)' or
   /// 'OpaqueValueExpr(expr) binop OpaqueValueExpr(x)'.
+  /// \param D 'd' part of the associated expression/statement.
+  /// \param Cond Conditional expression in `atomic compare` construct.
   /// \param IsXLHSInRHSPart true if \a UE has the first form and false if the
   /// second.
   /// \param IsPostfixUpdate true if original value of 'x' must be stored in
   /// 'v', not an updated one.
+  /// \param IsSignedOp true if the comparison operation is signed.
   static OMPAtomicDirective *
   Create(const ASTContext &C, SourceLocation StartLoc, SourceLocation EndLoc,
          ArrayRef<OMPClause *> Clauses, Stmt *AssociatedStmt, Expr *X, Expr *V,
-         Expr *E, Expr *UE, bool IsXLHSInRHSPart, bool IsPostfixUpdate);
+         Expr *E, Expr *UE, Expr *D, Expr *Cond, bool IsXLHSInRHSPart,
+         bool IsPostfixUpdate, bool IsSignedOp);
 
   /// Creates an empty directive with the place for \a NumClauses
   /// clauses.
@@ -2951,6 +2963,13 @@
   const Expr *getExpr() const {
     return cast_or_null<Expr>(Data->getChildren()[DataPositionTy::POS_E]);
   }
+  /// Get 'd' part of the associated expression/statement.
+  Expr *getD() {
+    return cast_or_null<Expr>(Data->getChildren()[DataPositionTy::POS_D]);
+  }
+  Expr *getD() const {
+    return cast_or_null<Expr>(Data->getChildren()[DataPositionTy::POS_D]);
+  }
 
   static bool classof(const Stmt *T) {
     return T->getStmtClass() == OMPAtomicDirectiveClass;
diff --git a/clang/lib/AST/StmtOpenMP.cpp b/clang/lib/AST/StmtOpenMP.cpp
--- a/clang/lib/AST/StmtOpenMP.cpp
+++ b/clang/lib/AST/StmtOpenMP.cpp
@@ -863,18 +863,23 @@
                                                    !IsStandalone);
 }
 
-OMPAtomicDirective *OMPAtomicDirective::Create(
-    const ASTContext &C, SourceLocation StartLoc, SourceLocation EndLoc,
-    ArrayRef<OMPClause *> Clauses, Stmt *AssociatedStmt, Expr *X, Expr *V,
-    Expr *E, Expr *UE, bool IsXLHSInRHSPart, bool IsPostfixUpdate) {
+OMPAtomicDirective *
+OMPAtomicDirective::Create(const ASTContext &C, SourceLocation StartLoc,
+                           SourceLocation EndLoc, ArrayRef<OMPClause *> Clauses,
+                           Stmt *AssociatedStmt, Expr *X, Expr *V, Expr *E,
+                           Expr *UE, Expr *D, Expr *Cond, bool IsXLHSInRHSPart,
+                           bool IsPostfixUpdate, bool IsSignedOp) {
   auto *Dir = createDirective<OMPAtomicDirective>(
-      C, Clauses, AssociatedStmt, /*NumChildren=*/4, StartLoc, EndLoc);
+      C, Clauses, AssociatedStmt, /*NumChildren=*/6, StartLoc, EndLoc);
   Dir->setX(X);
   Dir->setV(V);
   Dir->setExpr(E);
   Dir->setUpdateExpr(UE);
+  Dir->setD(D);
+  Dir->setCond(Cond);
   Dir->IsXLHSInRHSPart = IsXLHSInRHSPart;
   Dir->IsPostfixUpdate = IsPostfixUpdate;
+  Dir->IsSignedOp = IsSignedOp;
   return Dir;
 }
 
diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -11363,8 +11363,11 @@
   Expr *V = nullptr;
   Expr *E = nullptr;
   Expr *UE = nullptr;
+  Expr *D = nullptr;
+  Expr *CE = nullptr;
   bool IsXLHSInRHSPart = false;
   bool IsPostfixUpdate = false;
+  bool IsSignedOp = true;
   // OpenMP [2.12.6, atomic Construct]
   // In the next expressions:
   // * x and v (as applicable) are both l-value expressions with scalar type.
@@ -11759,18 +11762,20 @@
           << ErrorInfo.Error << ErrorInfo.NoteRange;
       return StmtError();
     }
-    // TODO: For now we emit an error here and in emitOMPAtomicExpr we ignore
-    // code gen.
-    unsigned DiagID = Diags.getCustomDiagID(
-        DiagnosticsEngine::Error, "atomic compare is not supported for now");
-    Diag(AtomicKindLoc, DiagID);
+    X = Checker.getX();
+    E = Checker.getE();
+    CE = Checker.getCond();
+    D = Checker.getD();
+    IsSignedOp = Checker.isSignedOp();
+    // We reuse this boolean variable.
+    IsXLHSInRHSPart = Checker.isXBinopExpr();
   }
 
   setFunctionHasBranchProtectedScope();
 
   return OMPAtomicDirective::Create(Context, StartLoc, EndLoc, Clauses, AStmt,
-                                    X, V, E, UE, IsXLHSInRHSPart,
-                                    IsPostfixUpdate);
+                                    X, V, E, UE, D, CE, IsXLHSInRHSPart,
+                                    IsPostfixUpdate, IsSignedOp);
 }
 
 StmtResult Sema::ActOnOpenMPTargetDirective(ArrayRef<OMPClause *> Clauses,