diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index dbf8155..97844cd 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -3447,6 +3447,7 @@
   case OMPD_declare_target:
   case OMPD_end_declare_target:
   case OMPD_requires:
+  case OMPD_declare_variant:
     llvm_unreachable("OpenMP Directive is not allowed");
   case OMPD_unknown:
     llvm_unreachable("Unknown OpenMP directive");
@@ -4516,6 +4517,7 @@
   case OMPD_declare_mapper:
   case OMPD_declare_simd:
   case OMPD_requires:
+  case OMPD_declare_variant:
     llvm_unreachable("OpenMP Directive is not allowed");
   case OMPD_unknown:
     llvm_unreachable("Unknown OpenMP directive");
@@ -4653,8 +4655,10 @@
   if (!DG || DG.get().isNull())
     return DeclGroupPtrTy();
 
+  const int SimdId = 0;
   if (!DG.get().isSingleDecl()) {
-    Diag(SR.getBegin(), diag::err_omp_single_decl_in_declare_simd);
+    Diag(SR.getBegin(), diag::err_omp_single_decl_in_declare_simd_variant)
+        << SimdId;
     return DG;
   }
   Decl *ADecl = DG.get().getSingleDecl();
@@ -4663,7 +4667,7 @@
 
   auto *FD = dyn_cast<FunctionDecl>(ADecl);
   if (!FD) {
-    Diag(ADecl->getLocation(), diag::err_omp_function_expected);
+    Diag(ADecl->getLocation(), diag::err_omp_function_expected) << SimdId;
     return DeclGroupPtrTy();
   }
 
@@ -4888,6 +4892,204 @@
   return ConvertDeclToDeclGroup(ADecl);
 }
 
+Sema::DeclGroupPtrTy
+Sema::ActOnOpenMPDeclareVariantDirective(Sema::DeclGroupPtrTy DG,
+                                         Expr *VariantRef, SourceRange SR) {
+  if (!DG || DG.get().isNull())
+    return DeclGroupPtrTy();
+
+  const int VariantId = 1;
+  // Must be applied only to single decl.
+  if (!DG.get().isSingleDecl()) {
+    Diag(SR.getBegin(), diag::err_omp_single_decl_in_declare_simd_variant)
+        << VariantId << SR;
+    return DG;
+  }
+  Decl *ADecl = DG.get().getSingleDecl();
+  if (auto *FTD = dyn_cast<FunctionTemplateDecl>(ADecl))
+    ADecl = FTD->getTemplatedDecl();
+
+  // Decl must be a function.
+  auto *FD = dyn_cast<FunctionDecl>(ADecl);
+  if (!FD) {
+    Diag(ADecl->getLocation(), diag::err_omp_function_expected)
+        << VariantId << SR;
+    return DeclGroupPtrTy();
+  }
+
+  auto &&HasMultiVersionAttributes = [](const FunctionDecl *FD) {
+    return FD->hasAttrs() &&
+           (FD->hasAttr<CPUDispatchAttr>() || FD->hasAttr<CPUSpecificAttr>() ||
+            FD->hasAttr<TargetAttr>());
+  };
+  // OpenMP is not compatible with CPU-specific attributes.
+  if (HasMultiVersionAttributes(FD)) {
+    Diag(FD->getLocation(), diag::err_omp_declare_variant_incompat_attributes)
+        << SR;
+    return DG;
+  }
+
+  // Allow #pragma omp declare variant only if the function is not used.
+  if (FD->isUsed(false)) {
+    Diag(SR.getBegin(), diag::err_omp_declare_variant_after_used)
+        << FD->getLocation();
+    return DG;
+  }
+
+  // The VariantRef must point to function.
+  if (!VariantRef) {
+    Diag(SR.getBegin(), diag::err_omp_function_expected) << VariantId;
+    return DG;
+  }
+
+  // Do not check templates, wait until instantiation.
+  if (VariantRef->isTypeDependent() || VariantRef->isValueDependent() ||
+      VariantRef->containsUnexpandedParameterPack() ||
+      VariantRef->isInstantiationDependent() || FD->isDependentContext())
+    return DG;
+
+  // Convert VariantRef expression to the type of the original function to
+  // resolve possible conflicts.
+  ExprResult VariantRefCast;
+  if (LangOpts.CPlusPlus) {
+    QualType FnPtrType;
+    auto *Method = dyn_cast<CXXMethodDecl>(FD);
+    if (Method && !Method->isStatic()) {
+      const Type *ClassType =
+          Context.getTypeDeclType(Method->getParent()).getTypePtr();
+      FnPtrType = Context.getMemberPointerType(FD->getType(), ClassType);
+      ExprResult ER;
+      {
+        // Build adrr_of unary op to correctly handle type checks for member
+        // functions.
+        Sema::TentativeAnalysisScope Trap(*this);
+        ER = CreateBuiltinUnaryOp(VariantRef->getBeginLoc(), UO_AddrOf,
+                                  VariantRef);
+      }
+      if (!ER.isUsable()) {
+        Diag(VariantRef->getExprLoc(), diag::err_omp_function_expected)
+            << VariantId << VariantRef->getSourceRange();
+        return DG;
+      }
+      VariantRef = ER.get();
+    } else {
+      FnPtrType = Context.getPointerType(FD->getType());
+    }
+    ImplicitConversionSequence ICS =
+        TryImplicitConversion(VariantRef, FnPtrType.getUnqualifiedType(),
+                              /*SuppressUserConversions=*/false,
+                              /*AllowExplicit=*/false,
+                              /*InOverloadResolution=*/false,
+                              /*CStyle=*/false,
+                              /*AllowObjCWritebackConversion=*/false);
+    if (ICS.isFailure()) {
+      Diag(VariantRef->getExprLoc(),
+           diag::err_omp_declare_variant_incompat_types)
+          << VariantRef->getType() << FnPtrType << VariantRef->getSourceRange();
+      return DG;
+    }
+    VariantRefCast = PerformImplicitConversion(
+        VariantRef, FnPtrType.getUnqualifiedType(), AA_Converting);
+    if (!VariantRefCast.isUsable())
+      return DG;
+    // Drop previously built artificial addr_of unary op for member functions.
+    if (Method && !Method->isStatic()) {
+      Expr *PossibleAddrOfVariantRef = VariantRefCast.get();
+      if (auto *UO = dyn_cast<UnaryOperator>(
+              PossibleAddrOfVariantRef->IgnoreImplicit()))
+        VariantRefCast = UO->getSubExpr();
+    }
+  } else {
+    VariantRefCast = VariantRef;
+  }
+
+  ExprResult ER = CheckPlaceholderExpr(VariantRefCast.get());
+  if (!ER.isUsable() ||
+      !ER.get()->IgnoreParenImpCasts()->getType()->isFunctionType()) {
+    Diag(VariantRef->getExprLoc(), diag::err_omp_function_expected)
+        << VariantId << VariantRef->getSourceRange();
+    return DG;
+  }
+
+  // The VariantRef must point to function.
+  auto *DRE = dyn_cast<DeclRefExpr>(ER.get()->IgnoreParenImpCasts());
+  if (!DRE) {
+    Diag(VariantRef->getExprLoc(), diag::err_omp_function_expected)
+        << VariantId << VariantRef->getSourceRange();
+    return DG;
+  }
+  auto *NewFD = dyn_cast_or_null<FunctionDecl>(DRE->getDecl());
+  if (!NewFD) {
+    Diag(VariantRef->getExprLoc(), diag::err_omp_function_expected)
+        << VariantId << VariantRef->getSourceRange();
+    return DG;
+  }
+
+  enum DoesntSupport {
+    VirtFuncs = 1,
+    Constructors = 3,
+    Destructors = 4,
+    DeletedFuncs = 5,
+    DefaultedFuncs = 6,
+    ConstexprFuncs = 7,
+    ConstevalFuncs = 8,
+  };
+  if (const auto *CXXFD = dyn_cast<CXXMethodDecl>(FD)) {
+    if (CXXFD->isVirtual()) {
+      Diag(FD->getLocation(), diag::err_omp_declare_variant_doesnt_support)
+          << VirtFuncs;
+      return DG;
+    }
+
+    if (isa<CXXConstructorDecl>(FD)) {
+      Diag(FD->getLocation(), diag::err_omp_declare_variant_doesnt_support)
+          << Constructors;
+      return DG;
+    }
+
+    if (isa<CXXDestructorDecl>(FD)) {
+      Diag(FD->getLocation(), diag::err_omp_declare_variant_doesnt_support)
+          << Destructors;
+      return DG;
+    }
+  }
+
+  if (FD->isDeleted()) {
+    Diag(FD->getLocation(), diag::err_omp_declare_variant_doesnt_support)
+        << DeletedFuncs;
+    return DG;
+  }
+
+  if (FD->isDefaulted()) {
+    Diag(FD->getLocation(), diag::err_omp_declare_variant_doesnt_support)
+        << DefaultedFuncs;
+    return DG;
+  }
+
+  if (FD->isConstexpr()) {
+    Diag(FD->getLocation(), diag::err_omp_declare_variant_doesnt_support)
+        << (NewFD->isConsteval() ? ConstevalFuncs : ConstexprFuncs);
+    return DG;
+  }
+
+  // Check general compatibility.
+  if (areMultiversionVariantFunctionsCompatible(
+          FD, NewFD, PDiag(diag::err_omp_declare_variant_noproto),
+          PartialDiagnosticAt(
+              SR.getBegin(),
+              PDiag(diag::note_omp_declare_variant_specified_here) << SR),
+          PartialDiagnosticAt(
+              VariantRef->getExprLoc(),
+              PDiag(diag::err_omp_declare_variant_doesnt_support)),
+          PartialDiagnosticAt(VariantRef->getExprLoc(),
+                              PDiag(diag::err_omp_declare_variant_diff)
+                                  << FD->getLocation()),
+          /*TemplatesSupported=*/true, /*ConstexprSupported=*/false))
+    return DG;
+
+  return DG;
+}
+
 StmtResult Sema::ActOnOpenMPParallelDirective(ArrayRef<OMPClause *> Clauses,
                                               Stmt *AStmt,
                                               SourceLocation StartLoc,
@@ -9895,6 +10097,7 @@
     case OMPD_declare_reduction:
     case OMPD_declare_mapper:
     case OMPD_declare_simd:
+    case OMPD_declare_variant:
     case OMPD_declare_target:
     case OMPD_end_declare_target:
     case OMPD_teams:
@@ -9963,6 +10166,7 @@
     case OMPD_declare_reduction:
     case OMPD_declare_mapper:
     case OMPD_declare_simd:
+    case OMPD_declare_variant:
     case OMPD_declare_target:
     case OMPD_end_declare_target:
     case OMPD_teams:
@@ -10032,6 +10236,7 @@
     case OMPD_declare_reduction:
     case OMPD_declare_mapper:
     case OMPD_declare_simd:
+    case OMPD_declare_variant:
     case OMPD_declare_target:
     case OMPD_end_declare_target:
     case OMPD_simd:
@@ -10098,6 +10303,7 @@
     case OMPD_declare_reduction:
     case OMPD_declare_mapper:
     case OMPD_declare_simd:
+    case OMPD_declare_variant:
     case OMPD_declare_target:
     case OMPD_end_declare_target:
     case OMPD_simd:
@@ -10165,6 +10371,7 @@
     case OMPD_declare_reduction:
     case OMPD_declare_mapper:
     case OMPD_declare_simd:
+    case OMPD_declare_variant:
     case OMPD_declare_target:
     case OMPD_end_declare_target:
     case OMPD_simd:
@@ -10231,6 +10438,7 @@
     case OMPD_declare_reduction:
     case OMPD_declare_mapper:
     case OMPD_declare_simd:
+    case OMPD_declare_variant:
     case OMPD_declare_target:
     case OMPD_end_declare_target:
     case OMPD_simd:
@@ -10296,6 +10504,7 @@
     case OMPD_declare_reduction:
     case OMPD_declare_mapper:
     case OMPD_declare_simd:
+    case OMPD_declare_variant:
     case OMPD_declare_target:
     case OMPD_end_declare_target:
     case OMPD_simd: