diff --git a/clang/include/clang/AST/CXXRecordDeclDefinitionBits.def b/clang/include/clang/AST/CXXRecordDeclDefinitionBits.def
index 9b270682f8cf0..cdf0804680ad0 100644
--- a/clang/include/clang/AST/CXXRecordDeclDefinitionBits.def
+++ b/clang/include/clang/AST/CXXRecordDeclDefinitionBits.def
@@ -112,6 +112,9 @@ FIELD(HasVariantMembers, 1, NO_MERGE)
 /// True if there no non-field members declared by the user.
 FIELD(HasOnlyCMembers, 1, NO_MERGE)
 
+/// True if there is an '__init' method defined by the user.
+FIELD(HasInitMethod, 1, NO_MERGE)
+
 /// True if any field has an in-class initializer, including those
 /// within anonymous unions or structs.
 FIELD(HasInClassInitializer, 1, NO_MERGE)
diff --git a/clang/include/clang/AST/DeclCXX.h b/clang/include/clang/AST/DeclCXX.h
index b54e6b0ac2171..2833df0505dac 100644
--- a/clang/include/clang/AST/DeclCXX.h
+++ b/clang/include/clang/AST/DeclCXX.h
@@ -1139,6 +1139,9 @@ class CXXRecordDecl : public RecordDecl {
   /// \note This does NOT include a check for union-ness.
   bool isEmpty() const { return data().Empty; }
 
+  void setInitMethod(bool Val) { data().HasInitMethod = Val; }
+  bool hasInitMethod() const { return data().HasInitMethod; }
+
   bool hasPrivateFields() const {
     return data().HasPrivateFields;
   }
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 17319c34f27b6..51be4d834c6b0 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -11493,6 +11493,10 @@ def warn_sycl_kernel_return_type : Warning<
   "function template with 'sycl_kernel' attribute must have a 'void' return type">,
   InGroup<IgnoredAttributes>;
 
+def err_sycl_special_type_num_init_method : Error<
+  "types with 'sycl_special_class' attribute must have one and only one '__init' "
+  "method defined">;
+
 def err_bit_int_bad_size : Error<"%select{signed|unsigned}0 _BitInt must "
                                  "have a bit size of at least %select{2|1}0">;
 def err_bit_int_max_size : Error<"%select{signed|unsigned}0 _BitInt of bit "
diff --git a/clang/lib/AST/DeclCXX.cpp b/clang/lib/AST/DeclCXX.cpp
index 108113274b8e0..187680a4ef1f9 100644
--- a/clang/lib/AST/DeclCXX.cpp
+++ b/clang/lib/AST/DeclCXX.cpp
@@ -81,8 +81,7 @@ CXXRecordDecl::DefinitionData::DefinitionData(CXXRecordDecl *D)
       HasPublicFields(false), HasMutableFields(false), HasVariantMembers(false),
       HasOnlyCMembers(true), HasInClassInitializer(false),
       HasUninitializedReferenceMember(false), HasUninitializedFields(false),
-      HasInheritedConstructor(false),
-      HasInheritedDefaultConstructor(false),
+      HasInheritedConstructor(false), HasInheritedDefaultConstructor(false),
       HasInheritedAssignment(false),
       NeedOverloadResolutionForCopyConstructor(false),
       NeedOverloadResolutionForMoveConstructor(false),
@@ -111,7 +110,7 @@ CXXRecordDecl::DefinitionData::DefinitionData(CXXRecordDecl *D)
       HasDeclaredCopyAssignmentWithConstParam(false),
       IsAnyDestructorNoReturn(false), IsLambda(false),
       IsParsingBaseSpecifiers(false), ComputedVisibleConversions(false),
-      HasODRHash(false), Definition(D) {}
+      HasODRHash(false), Definition(D), HasInitMethod(false) {}
 
 CXXBaseSpecifier *CXXRecordDecl::DefinitionData::getBasesSlowCase() const {
   return Bases.get(Definition->getASTContext().getExternalSource());
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index b997024bcda20..f3cca82e60e02 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -9194,6 +9194,13 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
         Diag(D.getDeclSpec().getVirtualSpecLoc(), diag::err_virtual_in_union);
         NewFD->setInvalidDecl();
       }
+      if ((Parent->isClass() || Parent->isStruct()) &&
+          Parent->hasAttr<SYCLSpecialClassAttr>() &&
+          NewFD->getKind() == Decl::Kind::CXXMethod && NewFD->getIdentifier() &&
+          NewFD->getName() == "__init" && D.isFunctionDefinition()) {
+        if (auto *Def = Parent->getDefinition())
+          Def->setInitMethod(true);
+      }
     }
 
     SetNestedNameSpecifier(*this, NewFD, D);
@@ -16764,8 +16771,21 @@ void Sema::ActOnTagFinishDefinition(Scope *S, Decl *TagD,
       RD->completeDefinition();
   }
 
-  if (isa<CXXRecordDecl>(Tag)) {
+  if (auto *RD = dyn_cast<CXXRecordDecl>(Tag)) {
     FieldCollector->FinishClass();
+    if (RD->hasAttr<SYCLSpecialClassAttr>() && getLangOpts().SYCLIsDevice) {
+      auto *Def = RD->getDefinition();
+      assert(Def && "The record is expected to have a completed definition");
+      unsigned NumInitMethods = 0;
+      for (auto *Method : Def->methods()) {
+        if (!Method->getIdentifier())
+          continue;
+        if (Method->getName() == "__init")
+          NumInitMethods++;
+      }
+      if (NumInitMethods > 1 || !Def->hasInitMethod())
+        Diag(RD->getLocation(), diag::err_sycl_special_type_num_init_method);
+    }
   }
 
   // Exit this scope of this tag's definition.
diff --git a/sycl/include/CL/sycl/accessor.hpp b/sycl/include/CL/sycl/accessor.hpp
index ba2f5e15f373a..cf13264b4fca0 100644
--- a/sycl/include/CL/sycl/accessor.hpp
+++ b/sycl/include/CL/sycl/accessor.hpp
@@ -2200,8 +2200,8 @@ class __SYCL_SPECIAL_CLASS accessor<DataT, Dimensions, AccessMode,
 /// \ingroup sycl_api_acc
 template <typename DataT, int Dimensions, access::mode AccessMode,
           access::placeholder IsPlaceholder>
-class __SYCL_SPECIAL_CLASS accessor<DataT, Dimensions, AccessMode,
-                                    access::target::host_image, IsPlaceholder>
+class accessor<DataT, Dimensions, AccessMode, access::target::host_image,
+               IsPlaceholder>
     : public detail::image_accessor<DataT, Dimensions, AccessMode,
                                     access::target::host_image, IsPlaceholder> {
 public: