diff --git a/clang/include/clang/AST/APValue.h b/clang/include/clang/AST/APValue.h
index 21647ffa5ac5a4..892a7f165a5fc7 100644
--- a/clang/include/clang/AST/APValue.h
+++ b/clang/include/clang/AST/APValue.h
@@ -32,6 +32,7 @@ template <typename T> class BasicReaderBase;
 
   class AddrLabelExpr;
   class ASTContext;
+  class AttributeCommonInfo;
   class CharUnits;
   class CXX26AnnotationAttr;
   class CXXRecordDecl;
@@ -489,6 +490,10 @@ class APValue {
     return isReflection() && getReflectionKind() == ReflectionKind::Annotation;
   }
 
+  bool isReflectedAttribute() const {
+    return isReflection() && getReflectionKind() == ReflectionKind::Attribute;
+  }
+
   void dump() const;
   void dump(raw_ostream &OS, const ASTContext &Context) const;
 
@@ -678,6 +683,7 @@ class APValue {
   CXXBaseSpecifier *getReflectedBaseSpecifier() const;
   TagDataMemberSpec *getReflectedDataMemberSpec() const;
   CXX26AnnotationAttr *getReflectedAnnotation() const;
+  AttributeCommonInfo *getReflectedAttribute() const;
 
   void setInt(APSInt I) {
     assert(isInt() && "Invalid accessor");
diff --git a/clang/include/clang/AST/ExprCXX.h b/clang/include/clang/AST/ExprCXX.h
index ea12345ea49f55..134c7e49081b3f 100644
--- a/clang/include/clang/AST/ExprCXX.h
+++ b/clang/include/clang/AST/ExprCXX.h
@@ -5321,7 +5321,8 @@ class BuiltinBitCastExpr final
 };
 
 /// Represents a C++2c reflect expression (P2996). The operand of the expression
-/// is either a type, an expression, a template-name, or a namespace.
+/// is either a type, an expression, a template-name, an attribute or a
+/// namespace.
 class CXXReflectExpr : public Expr {
   enum class OperandKind {
     Unset,
@@ -5408,12 +5409,12 @@ class CXXReflectExpr : public Expr {
 /// reflections (P2996). Arguments vary by function.
 class CXXMetafunctionExpr : public Expr {
 public:
-  // Type of callback provided to executing metafunctinons to help evaluate an
+  // Type of callback provided to executing metafunctions to help evaluate an
   // expression in the current constant evaluation context.
   using EvaluateFn = std::function<bool(APValue &, const Expr *,
                                         bool ConvertToRValue)>;
 
-  // Type of callback provided to report a diagnistc to the evaluation context.
+  // Type of callback provided to report a diagnostic to the evaluation context.
   using DiagnoseFn = std::function<PartialDiagnostic &(SourceLocation,
                                                        unsigned)>;
 
diff --git a/clang/include/clang/AST/RecursiveASTVisitor.h b/clang/include/clang/AST/RecursiveASTVisitor.h
index 9dd8528c04f470..268c8bafdb6c88 100644
--- a/clang/include/clang/AST/RecursiveASTVisitor.h
+++ b/clang/include/clang/AST/RecursiveASTVisitor.h
@@ -2991,6 +2991,7 @@ DEF_TRAVERSE_STMT(CXXReflectExpr, {
     case ReflectionKind::Namespace:
     case ReflectionKind::BaseSpecifier:
     case ReflectionKind::DataMemberSpec:
+    case ReflectionKind::Attribute: // TODO P3385 ?
       break;
     }
   }
diff --git a/clang/include/clang/AST/Reflection.h b/clang/include/clang/AST/Reflection.h
index 5838d310e00c5f..fde146b47d4240 100644
--- a/clang/include/clang/AST/Reflection.h
+++ b/clang/include/clang/AST/Reflection.h
@@ -48,7 +48,7 @@ enum class ReflectionKind {
   ///
   /// Corresponds to an APValue (plus a QualType).
   Object,
-  
+
   /// \brief A reflection of a value (i.e., the result of a prvalue).
   ///
   /// Corresponds to an APValue (plus a QualType).
@@ -102,8 +102,10 @@ enum class ReflectionKind {
 
   /// \brief A reflection of an annotation (P2996 ext).
   Annotation,
-};
 
+  /// \brief A reflection of a standard attribute (P3385).
+  Attribute,
+};
 
 /// \brief Representation of a hypothetical data member, which could be used to
 /// complete an incomplete class definition using the 'std::meta::define_class'
diff --git a/clang/include/clang/Basic/DiagnosticMetafnKinds.td b/clang/include/clang/Basic/DiagnosticMetafnKinds.td
index 3bd7a0019a666d..39150bd411d5ef 100644
--- a/clang/include/clang/Basic/DiagnosticMetafnKinds.td
+++ b/clang/include/clang/Basic/DiagnosticMetafnKinds.td
@@ -18,7 +18,7 @@ def metafn_no_associated_property : Note<
   "%0 has no %select{type|parent}1">;
 def metafn_cannot_query_property : Note<"cannot query the "
   "%select{type|object|value|size|alignment|parameters|return type|"
-           "annotations}0 of %1">;
+           "annotations|attributes}0 of %1">;
 
 // Ranges of entities.
 def metafn_cannot_introspect_type : Note<
@@ -89,6 +89,11 @@ def metafn_value_not_structural_type : Note<
 def metafn_result_not_representable : Note<
   "provided %select{value|object}0 cannot be represented by a reflection">;
 
+def metafn_p3385_trace_execution_checkpoint : Warning<
+  "(p3385-metafn) trace_execution_checkpoint %0">;
+def metafn_p3385_non_standard_attribute : Warning<
+  "(p3385-metafn) Non standard attribute discovered %0">;
+
 // Class definition.
 def metafn_name_invalid_identifier : Note<
   "provided name '%0' is not a valid identifier">;
diff --git a/clang/include/clang/Basic/DiagnosticParseKinds.td b/clang/include/clang/Basic/DiagnosticParseKinds.td
index f7a9a698911b2a..28ba5a17b349e6 100644
--- a/clang/include/clang/Basic/DiagnosticParseKinds.td
+++ b/clang/include/clang/Basic/DiagnosticParseKinds.td
@@ -1746,6 +1746,20 @@ def err_annotation_with_using : Error<
   "annotations are not permitted following an attribute-using-prefix">;
 }
 
+let CategoryName = "P3385" in {
+
+def p3385_trace_attribute_parsed : Warning<
+  "(p3385) found attribute to parse following caret operator">;
+def p3385_trace_empty_attributes_list : Warning<
+  "(p3385) reflection of an empty attribute list">;
+def p3385_trace_execution_checkpoint : Warning<
+  "(p3385) trace_execution_checkpoint %0">;
+def p3385_err_attributes_list : Error<
+  "(p3385) reflection of attribute list is not supported, found %0 attributes">;
+def p3385_err_attribute_splicing_error : Error<
+  "(p3385) splicing of attributes error: %0">;
+}
+
 let CategoryName = "Generics Issue" in {
 
 def err_objc_expected_type_parameter : Error<
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 5db541f3a87eb7..716df4fbcafcc5 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3173,6 +3173,9 @@ def note_dependent_splice_explicit_this_may_fix : Note<
 def err_cannot_expand_over_type : Error<
   "cannot expand over an expression of type %0">;
 
+def p3385_trace_building_attribute_reflection : Warning<
+  "(p3385) building a CXX reflection on attribute %0">;
+
 // C++11 char16_t/char32_t
 def warn_cxx98_compat_unicode_type : Warning<
   "'%0' type specifier is incompatible with C++98">,
diff --git a/clang/include/clang/Parse/Parser.h b/clang/include/clang/Parse/Parser.h
index f26e95fcd56b01..4039604838f427 100644
--- a/clang/include/clang/Parse/Parser.h
+++ b/clang/include/clang/Parse/Parser.h
@@ -316,6 +316,8 @@ class Parser : public CodeCompletionHandler {
 
   /// Factory object for creating ParsedAttr objects.
   AttributeFactory AttrFactory;
+  /// FIXNE P3385
+  ParsedAttributes Attrs;
 
   /// Gathers and cleans up TemplateIdAnnotations when parsing of a
   /// top-level declaration is finished.
@@ -3047,6 +3049,11 @@ class Parser : public CodeCompletionHandler {
     ParseCXX11AttributeSpecifierInternal(Attrs, OpenMPTokens, EndLoc);
     ReplayOpenMPAttributeTokens(OpenMPTokens);
   }
+
+  bool tryParseSpliceAttrSpecifier(ParsedAttributes &Attrs,
+                                   SourceLocation *EndLoc = nullptr);
+  /// Try parsing a splice expression when inside an attribute specifier
+
   void ParseCXX11Attributes(ParsedAttributes &attrs);
   /// Parses a C++11 (or C23)-style attribute argument list. Returns true
   /// if this results in adding an attribute to the ParsedAttributes list.
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 302caa65c0e2d1..e6de857724d7b0 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -35,6 +35,7 @@
 #include "clang/AST/Type.h"
 #include "clang/AST/TypeLoc.h"
 #include "clang/Basic/AttrSubjectMatchRules.h"
+#include "clang/Basic/AttributeCommonInfo.h"
 #include "clang/Basic/Builtins.h"
 #include "clang/Basic/CapturedStmt.h"
 #include "clang/Basic/Cuda.h"
@@ -15173,6 +15174,7 @@ class Sema final : public SemaBase {
   ExprResult ActOnCXXReflectExpr(SourceLocation OpLoc,
                                  ParsedTemplateArgument Template);
   ExprResult ActOnCXXReflectExpr(SourceLocation OpLoc, CXXSpliceExpr *E);
+  ExprResult ActOnCXXReflectExpr(SourceLocation OpLoc, ParsedAttr *a);
 
   ExprResult ActOnCXXMetafunction(SourceLocation KwLoc,
                                   SourceLocation LParenLoc,
@@ -15222,6 +15224,7 @@ class Sema final : public SemaBase {
   ExprResult BuildCXXReflectExpr(SourceLocation OperatorLoc,
                                  SourceLocation OperandLoc,
                                  TemplateName Template);
+  ExprResult BuildCXXReflectExpr(SourceLocation OperatorLoc, ParsedAttr *A);
 
   // Reflection of expression operands.
   ExprResult BuildCXXReflectExpr(SourceLocation OperatorLoc, Expr *E);
diff --git a/clang/lib/AST/APValue.cpp b/clang/lib/AST/APValue.cpp
index 3c65393d7e09a4..decb53c9f03caa 100644
--- a/clang/lib/AST/APValue.cpp
+++ b/clang/lib/AST/APValue.cpp
@@ -22,6 +22,7 @@
 #include "clang/AST/ExprCXX.h"
 #include "clang/AST/LocInfoType.h"
 #include "clang/AST/Type.h"
+#include "clang/Basic/AttributeCommonInfo.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 using namespace clang;
@@ -547,6 +548,7 @@ static void profileReflection(llvm::FoldingSetNodeID &ID, APValue V) {
   case ReflectionKind::Namespace:
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     ID.AddPointer(V.getOpaqueReflectionData());
     return;
   case ReflectionKind::DataMemberSpec: {
@@ -942,6 +944,13 @@ CXX26AnnotationAttr *APValue::getReflectedAnnotation() const {
           const_cast<void *>(getOpaqueReflectionData()));
 }
 
+AttributeCommonInfo *APValue::getReflectedAttribute() const {
+  assert(getReflectionKind() == ReflectionKind::Attribute &&
+         "not a reflection of an attribute");
+  return reinterpret_cast<AttributeCommonInfo *>(
+          const_cast<void *>(getOpaqueReflectionData()));
+}
+
 static double GetApproxValue(const llvm::APFloat &F) {
   llvm::APFloat V = F;
   bool ignored;
@@ -1295,6 +1304,9 @@ void APValue::printPretty(raw_ostream &Out, const PrintingPolicy &Policy,
     case ReflectionKind::Annotation:
       Repr = "annotation";
       break;
+    case ReflectionKind::Attribute:
+      Repr = "attribute";
+      break;
     }
     Out << "^^(" << Repr << ")";
     return;
@@ -1635,6 +1647,7 @@ void APValue::setReflection(ReflectionKind RK, const void *Ptr) {
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     SelfData.Kind = RK;
     SelfData.Data = Ptr;
     return;
diff --git a/clang/lib/AST/ComputeDependence.cpp b/clang/lib/AST/ComputeDependence.cpp
index a2608a5d0dd2a9..73327c39b6e741 100644
--- a/clang/lib/AST/ComputeDependence.cpp
+++ b/clang/lib/AST/ComputeDependence.cpp
@@ -986,6 +986,7 @@ ExprDependence clang::computeDependence(CXXReflectExpr *E,
   case ReflectionKind::Namespace:
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
+  case ReflectionKind::Attribute:
     return ExprDependence::None;
   }
   llvm_unreachable("unknown reflection kind while computing dependence");
diff --git a/clang/lib/AST/ExprConstantMeta.cpp b/clang/lib/AST/ExprConstantMeta.cpp
index aa1a14ac9ca746..77a2998e8decab 100644
--- a/clang/lib/AST/ExprConstantMeta.cpp
+++ b/clang/lib/AST/ExprConstantMeta.cpp
@@ -22,7 +22,10 @@
 #include "clang/AST/Metafunction.h"
 #include "clang/AST/RecordLayout.h"
 #include "clang/AST/Reflection.h"
+#include "clang/AST/Type.h"
+#include "clang/Basic/AttributeCommonInfo.h"
 #include "clang/Basic/DiagnosticMetafn.h"
+#include "clang/Basic/IdentifierTable.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Lex/Lexer.h"
 #include "clang/Lex/Preprocessor.h"
@@ -30,7 +33,6 @@
 #include "llvm/Support/Format.h"
 #include "llvm/Support/raw_ostream.h"
 
-
 namespace clang {
 
 using EvalFn = Metafunction::EvaluateFn;
@@ -558,6 +560,19 @@ static bool annotate(APValue &Result, ASTContext &C, MetaActions &Meta,
                      EvalFn Evaluator, DiagFn Diagnoser, QualType ResultTy,
                      SourceRange Range, ArrayRef<Expr *> Args);
 
+// -----------------------------------------------------------------------------
+// P3385 Metafunction declarations
+// -----------------------------------------------------------------------------
+
+static bool get_ith_attribute_of(APValue &Result, ASTContext &C,
+                                 MetaActions &Meta, EvalFn Evaluator,
+                                 DiagFn Diagnoser, QualType ResultTy,
+                                 SourceRange Range,
+                                 ArrayRef<Expr *> Args);
+
+static bool is_attribute(APValue &Result, ASTContext &C, MetaActions &Meta,
+                         EvalFn Evaluator, DiagFn Diagnoser, QualType ResultTy,
+                         SourceRange Range, ArrayRef<Expr *> Args);
 
 // -----------------------------------------------------------------------------
 // Metafunction table
@@ -686,6 +701,11 @@ static constexpr Metafunction Metafunctions[] = {
   { Metafunction::MFRK_metaInfo, 3, 3, get_ith_annotation_of },
   { Metafunction::MFRK_bool, 1, 1, is_annotation },
   { Metafunction::MFRK_metaInfo, 2, 2, annotate },
+
+  // P3385 attributes reflection
+  { Metafunction::MFRK_metaInfo, 3, 3, get_ith_attribute_of },
+  { Metafunction::MFRK_bool, 1, 1, is_attribute },
+
 };
 constexpr const unsigned NumMetafunctions = sizeof(Metafunctions) /
                                             sizeof(Metafunction);
@@ -748,6 +768,10 @@ static APValue makeReflection(CXX26AnnotationAttr *A) {
   return APValue(ReflectionKind::Annotation, A);
 }
 
+static APValue makeReflection(const AttributeCommonInfo * Attr) {
+  return APValue(ReflectionKind::Attribute, Attr);
+}
+
 static Expr *makeStrLiteral(StringRef Str, ASTContext &C, bool Utf8) {
   QualType ConstCharTy = (Utf8 ? C.Char8Ty : C.CharTy).withConst();
 
@@ -938,6 +962,15 @@ static bool findAnnotLoc(APValue &Result, ASTContext &C, EvalFn Evaluator,
   return !Evaluator(Result, SLE, true);
 }
 
+static bool findAttrLoc(APValue &Result, ASTContext &C, EvalFn Evaluator,
+                         QualType ResultTy, AttributeCommonInfo *A) {
+  SourceLocExpr *SLE =
+          new (C) SourceLocExpr(C, SourceLocIdentKind::SourceLocStruct,
+                                ResultTy, A->getLoc(), SourceLocation(),
+                                nullptr);
+  return !Evaluator(Result, SLE, true);
+}
+
 static QualType desugarType(QualType QT, bool UnwrapAliases, bool DropCV,
                             bool DropRefs) {
   bool IsConst = QT.isConstQualified();
@@ -1396,6 +1429,9 @@ StringRef DescriptionOf(APValue RV, bool Granular = true) {
   case ReflectionKind::Annotation: {
     return "an annotation";
   }
+  case ReflectionKind::Attribute: {
+    return "an attribute";
+  }
   }
 }
 
@@ -1416,6 +1452,82 @@ bool DiagnoseReflectionKind(DiagFn Diagnoser, SourceRange Range,
 // Metafunction implementations
 // -----------------------------------------------------------------------------
 
+bool get_ith_attribute_of(APValue &Result, ASTContext &C,
+                          MetaActions &Meta, EvalFn Evaluator,
+                          DiagFn Diagnoser, QualType ResultTy,
+                          SourceRange Range, ArrayRef<Expr *> Args) {
+  assert(Args[0]->getType()->isReflectionType());
+  assert(ResultTy == C.MetaInfoTy);
+
+  APValue RV;
+  if (!Evaluator(RV, Args[0], true))
+    return true;
+
+  APValue Sentinel;
+  if (!Evaluator(Sentinel, Args[1], true))
+    return true;
+  assert(Sentinel.isReflectedType());
+
+  APValue Idx;
+  if (!Evaluator(Idx, Args[2], true))
+    return true;
+  size_t idx = Idx.getInt().getExtValue();
+
+  switch (RV.getReflectionKind()) {
+    case ReflectionKind::Attribute: {
+      if (idx != 0) {
+      return SetAndSucceed(Result, Sentinel);
+      }
+      AttributeCommonInfo *attr = RV.getReflectedAttribute();
+      if (attr->getForm().getSyntax() == AttributeCommonInfo::Syntax::AS_CXX11) {
+        return SetAndSucceed(Result, makeReflection(attr));
+      }
+      // Non standard
+      return Diagnoser(Range.getBegin(), diag::metafn_p3385_non_standard_attribute) << attr->getAttrName();
+    }
+    case ReflectionKind::Type: {
+      QualType qType = RV.getReflectedType();
+      Decl *D = findTypeDecl(qType);
+      if (!D) {
+        // FIXME how would we end up here ?
+        return DiagnoseReflectionKind(Diagnoser, Range, "attribute or type",
+                                    DescriptionOf(RV));
+      }
+      auto attrs = D->attrs();
+      
+      if (attrs.empty()) {
+        return SetAndSucceed(Result, Sentinel);
+      }
+
+      // FIXME cache this...
+      if (auto* attr = attrs.begin(); attr != attrs.end()) {
+          while(idx != 0) {
+            ++attr;
+            --idx;
+            if (attr == attrs.end()) {
+              return SetAndSucceed(Result, Sentinel);
+            }
+          }
+          return SetAndSucceed(Result, makeReflection(*attr));
+      }
+      return SetAndSucceed(Result, Sentinel);
+    }
+    case ReflectionKind::Declaration:
+    case ReflectionKind::Null:
+    case ReflectionKind::Template:
+    case ReflectionKind::Object:
+    case ReflectionKind::Value:
+    case ReflectionKind::Namespace:
+    case ReflectionKind::BaseSpecifier:
+    case ReflectionKind::DataMemberSpec:
+    case ReflectionKind::Annotation:
+      return DiagnoseReflectionKind(Diagnoser, Range, "declaration or attribute",
+                                    DescriptionOf(RV));
+  }
+  llvm_unreachable("unknown reflection kind");
+  return false;
+}
+
 bool get_begin_enumerator_decl_of(APValue &Result, ASTContext &C,
                                   MetaActions &Meta, EvalFn Evaluator,
                                   DiagFn Diagnoser, QualType ResultTy,
@@ -1453,6 +1565,7 @@ bool get_begin_enumerator_decl_of(APValue &Result, ASTContext &C,
   case ReflectionKind::Namespace:
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
+  case ReflectionKind::Attribute:
   case ReflectionKind::Annotation: {
     return DiagnoseReflectionKind(Diagnoser, Range, "an enum type",
                                   DescriptionOf(RV));
@@ -1493,6 +1606,7 @@ bool get_next_enumerator_decl_of(APValue &Result, ASTContext &C,
   case ReflectionKind::Namespace:
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
+  case ReflectionKind::Attribute:
   case ReflectionKind::Annotation: {
     llvm_unreachable("should have failed in 'get_begin_enumerator_decl_of'");
   }
@@ -1550,6 +1664,7 @@ bool get_ith_base_of(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return DiagnoseReflectionKind(Diagnoser, Range, "a class type",
                                   DescriptionOf(RV));
   }
@@ -1604,6 +1719,7 @@ bool get_ith_template_argument_of(APValue &Result, ASTContext &C,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return DiagnoseReflectionKind(Diagnoser, Range, "a template specialization",
                                   DescriptionOf(RV));
   }
@@ -1693,6 +1809,7 @@ bool get_begin_member_decl_of(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return true;
   }
   llvm_unreachable("unknown reflection kind");
@@ -1871,6 +1988,11 @@ bool identifier_of(APValue &Result, ASTContext &C, MetaActions &Meta,
     getDeclName(Name, C, RV.getReflectedNamespace());
     break;
   }
+  case ReflectionKind::Attribute: {
+    AttributeCommonInfo* attr = RV.getReflectedAttribute();
+    Name = attr->getAttrName()->getName();
+    break;
+  }
   case ReflectionKind::DataMemberSpec: {
     TagDataMemberSpec *TDMS = RV.getReflectedDataMemberSpec();
     if (TDMS->Name)
@@ -1962,6 +2084,7 @@ bool has_identifier(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::Object:
   case ReflectionKind::Value:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     break;
   }
 
@@ -2049,6 +2172,9 @@ bool source_location_of(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::Annotation:
     return findAnnotLoc(Result, C, Evaluator, ResultTy,
                         RV.getReflectedAnnotation());
+  case ReflectionKind::Attribute:
+    return findAttrLoc(Result, C, Evaluator, ResultTy,
+                        RV.getReflectedAttribute());
   case ReflectionKind::Object:
   case ReflectionKind::Value:
   case ReflectionKind::Null:
@@ -2070,6 +2196,7 @@ bool type_of(APValue &Result, ASTContext &C, MetaActions &Meta,
   switch (RV.getReflectionKind()) {
   case ReflectionKind::Null:
   case ReflectionKind::Type:
+  case ReflectionKind::Attribute:
   case ReflectionKind::Template:
   case ReflectionKind::Namespace:
     return Diagnoser(Range.getBegin(), diag::metafn_no_associated_property)
@@ -2145,6 +2272,7 @@ bool parent_of(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     if (Diagnoser)
       return Diagnoser(Range.getBegin(), diag::metafn_no_associated_property)
           << DescriptionOf(RV) << 1 << Range;
@@ -2198,6 +2326,7 @@ bool dealias(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return SetAndSucceed(Result, RV);
   case ReflectionKind::Type: {
     QualType QT = RV.getReflectedType();
@@ -2259,6 +2388,7 @@ bool object_of(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return Diagnoser(Range.getBegin(), diag::metafn_cannot_query_property)
         << 1 << DescriptionOf(RV) << Range;
   }
@@ -2348,6 +2478,7 @@ bool value_of(APValue &Result, ASTContext &C, MetaActions &Meta,
                               /*DropCV=*/true, /*DropRefs=*/false);
     return SetAndSucceed(Result, A->getValue().Lift(Ty));
   }
+  case ReflectionKind::Attribute: // TODO P3385 anything to do ?
   case ReflectionKind::Null:
   case ReflectionKind::Type:
   case ReflectionKind::Template:
@@ -2395,6 +2526,7 @@ bool template_of(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return DiagnoseReflectionKind(Diagnoser, Range, "a template specialization",
                                   DescriptionOf(RV));
     return true;
@@ -2417,6 +2549,7 @@ static bool CanActAsTemplateArg(const APValue &RV) {
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
   case ReflectionKind::Null:
     return false;
   }
@@ -2837,6 +2970,7 @@ bool extract(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::Type:
   case ReflectionKind::Template:
   case ReflectionKind::Namespace:
+  case ReflectionKind::Attribute:
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
     return Diagnoser(Range.getBegin(), diag::metafn_cannot_extract)
@@ -2884,6 +3018,7 @@ bool is_public(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
   case ReflectionKind::Namespace:
+  case ReflectionKind::Attribute:
     return SetAndSucceed(Result, makeBool(C, false));
   }
   llvm_unreachable("invalid reflection type");
@@ -2927,6 +3062,7 @@ bool is_protected(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::Value:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
   case ReflectionKind::Namespace:
     return SetAndSucceed(Result, makeBool(C, false));
   }
@@ -2972,6 +3108,7 @@ bool is_private(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::Namespace:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return SetAndSucceed(Result, makeBool(C, false));
   }
   llvm_unreachable("invalid reflection type");
@@ -3026,6 +3163,7 @@ bool is_access_specified(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::Namespace:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return SetAndSucceed(Result, makeBool(C, false));
   }
   llvm_unreachable("invalid reflection type");
@@ -3134,6 +3272,7 @@ bool is_accessible(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::Namespace:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return DiagnoseReflectionKind(Diagnoser, Range, "a class member",
                                   DescriptionOf(RV));
   }
@@ -3169,7 +3308,8 @@ bool is_virtual(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::Namespace:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
-    return SetAndSucceed(Result, makeBool(C, IsVirtual));
+  case ReflectionKind::Attribute:
+    return SetAndSucceed(Result, makeBool(C, false));
   }
   llvm_unreachable("invalid reflection type");
 }
@@ -3194,6 +3334,7 @@ bool is_pure_virtual(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return SetAndSucceed(Result, makeBool(C, false));
   case ReflectionKind::Declaration: {
     bool IsPureVirtual = false;
@@ -3227,6 +3368,7 @@ bool is_override(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return SetAndSucceed(Result, makeBool(C, false));
   case ReflectionKind::Declaration: {
     if (const auto *MD = dyn_cast<CXXMethodDecl>(RV.getReflectedDecl()))
@@ -3257,6 +3399,7 @@ bool is_deleted(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return SetAndSucceed(Result, makeBool(C, false));
   case ReflectionKind::Declaration: {
     bool IsDeleted = false;
@@ -3288,6 +3431,7 @@ bool is_defaulted(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return SetAndSucceed(Result, makeBool(C, false));
   case ReflectionKind::Declaration: {
     bool IsDefaulted = false;
@@ -3319,6 +3463,7 @@ bool is_explicit(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
   case ReflectionKind::Template:
     return SetAndSucceed(Result, makeBool(C, false));
   case ReflectionKind::Declaration: {
@@ -3354,6 +3499,7 @@ bool is_noexcept(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return SetAndSucceed(Result, makeBool(C, false));
   case ReflectionKind::Type: {
     const QualType QT = RV.getReflectedType();
@@ -3425,6 +3571,7 @@ bool is_const(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return SetAndSucceed(Result, makeBool(C, false));
   case ReflectionKind::Type: {
     bool result = isConstQualifiedType(RV.getReflectedType());
@@ -3465,6 +3612,7 @@ bool is_volatile(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return SetAndSucceed(Result, makeBool(C, false));
   case ReflectionKind::Type: {
     bool result = isVolatileQualifiedType(RV.getReflectedType());
@@ -3807,7 +3955,8 @@ bool is_static_member(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
-    return SetAndSucceed(Result, makeBool(C, result));
+  case ReflectionKind::Attribute:
+    return SetAndSucceed(Result, makeBool(C, false));
   }
   llvm_unreachable("unknown reflection kind");
 }
@@ -3851,6 +4000,18 @@ bool is_namespace(APValue &Result, ASTContext &C, MetaActions &Meta,
   return SetAndSucceed(Result, makeBool(C, RV.isReflectedNamespace()));
 }
 
+bool is_attribute(APValue &Result, ASTContext &C, MetaActions &Meta,
+                  EvalFn Evaluator, DiagFn Diagnoser, QualType ResultTy,
+                  SourceRange Range, ArrayRef<Expr *> Args) {
+  assert(Args[0]->getType()->isReflectionType());
+  assert(ResultTy == C.BoolTy);
+  APValue RV;
+  if (!Evaluator(RV, Args[0], true))
+    return true;
+
+  return SetAndSucceed(Result, makeBool(C, RV.isReflectedAttribute()));
+}
+
 bool is_function(APValue &Result, ASTContext &C, MetaActions &Meta,
                  EvalFn Evaluator, DiagFn Diagnoser, QualType ResultTy,
                  SourceRange Range, ArrayRef<Expr *> Args) {
@@ -3927,6 +4088,7 @@ bool is_alias(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return SetAndSucceed(Result, makeBool(C, false));
   }
   llvm_unreachable("unknown reflection kind");
@@ -3988,6 +4150,7 @@ bool has_complete_definition(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     break;
   }
 
@@ -4262,6 +4425,7 @@ bool has_template_arguments(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return SetAndSucceed(Result, makeBool(C, false));
   }
   llvm_unreachable("unknown reflection kind");
@@ -4361,6 +4525,7 @@ bool is_constructor(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return SetAndSucceed(Result, makeBool(C, false));
   case ReflectionKind::Declaration: {
     bool result = isa<CXXConstructorDecl>(RV.getReflectedDecl());
@@ -4499,6 +4664,7 @@ bool is_destructor(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return SetAndSucceed(Result, makeBool(C, false));
   case ReflectionKind::Declaration: {
     bool result = isa<CXXDestructorDecl>(RV.getReflectedDecl());
@@ -4528,6 +4694,7 @@ bool is_special_member_function(APValue &Result, ASTContext &C,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return SetAndSucceed(Result, makeBool(C, false));
   case ReflectionKind::Declaration: {
     bool IsSpecial = false;
@@ -4783,6 +4950,7 @@ bool reflect_invoke(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return Diagnoser(Range.getBegin(), diag::metafn_cannot_invoke)
         << DescriptionOf(FnRefl) << Range;
   case ReflectionKind::Object: {
@@ -5146,6 +5314,7 @@ bool offset_of(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return DiagnoseReflectionKind(Diagnoser, Range, "a non-static data member",
                                   DescriptionOf(RV));
   case ReflectionKind::Declaration: {
@@ -5202,6 +5371,7 @@ bool size_of(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::Namespace:
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return Diagnoser(Range.getBegin(), diag::metafn_cannot_query_property)
         << 3 << DescriptionOf(RV);
   }
@@ -5228,6 +5398,7 @@ bool bit_offset_of(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return DiagnoseReflectionKind(Diagnoser, Range, "a non-static data member",
                                   DescriptionOf(RV));
   case ReflectionKind::Declaration: {
@@ -5290,6 +5461,7 @@ bool bit_size_of(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::Namespace:
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return Diagnoser(Range.getBegin(), diag::metafn_cannot_query_property)
         << 3 << DescriptionOf(RV);
   }
@@ -5353,6 +5525,7 @@ bool alignment_of(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::Namespace:
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return Diagnoser(Range.getBegin(), diag::metafn_cannot_query_property)
         << 4 << DescriptionOf(RV) << Range;
   }
@@ -5541,6 +5714,7 @@ bool get_ith_parameter_of(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return true;
   }
   return Diagnoser(Range.getBegin(), diag::metafn_cannot_query_property)
@@ -5576,6 +5750,7 @@ bool has_consistent_identifier(APValue &Result, ASTContext &C,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return has_identifier(Result, C, Meta, Evaluator, Diagnoser, ResultTy,
                           Range, Args);
   }
@@ -5602,6 +5777,7 @@ bool has_ellipsis_parameter(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return Diagnoser(Range.getBegin(), diag::metafn_cannot_query_property)
       << 5 << DescriptionOf(RV) << Range;
   case ReflectionKind::Type:
@@ -5648,6 +5824,7 @@ bool has_default_argument(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return DiagnoseReflectionKind(Diagnoser, Range, "a function parameter",
                                   DescriptionOf(RV));
   }
@@ -5722,6 +5899,7 @@ bool return_type_of(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return Diagnoser(Range.getBegin(), diag::metafn_cannot_query_property)
         << 6 << DescriptionOf(RV) << Range;
   }
@@ -5794,6 +5972,7 @@ bool get_ith_annotation_of(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return Diagnoser(Range.getBegin(), diag::metafn_cannot_query_property)
         << 7 << DescriptionOf(RV) << Range;
   }
@@ -5868,6 +6047,7 @@ bool annotate(APValue &Result, ASTContext &C, MetaActions &Meta,
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     return Diagnoser(Range.getBegin(), diag::metafn_cannot_annotate)
         << DescriptionOf(Appertainee) << Range;
   }
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index fe46d6a86da5a4..96bba3244a03d0 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -14,10 +14,13 @@
 
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/DeclTemplate.h"
+#include "clang/AST/ExprCXX.h"
 #include "clang/AST/PrettyDeclStackTrace.h"
+#include "clang/AST/Reflection.h"
 #include "clang/Basic/AttributeCommonInfo.h"
 #include "clang/Basic/Attributes.h"
 #include "clang/Basic/CharInfo.h"
+#include "clang/Basic/DiagnosticParse.h"
 #include "clang/Basic/OperatorKinds.h"
 #include "clang/Basic/TargetInfo.h"
 #include "clang/Basic/TokenKinds.h"
@@ -5041,11 +5044,131 @@ bool Parser::ParseCXX11AttributeArgs(
   return true;
 }
 
+// FIXME I'm copypasting this straight from ExprConstantMeta
+//
+static NamedDecl *findTypeDecl(QualType QT) {
+  // If it's an ElaboratedType, get the underlying NamedType.
+  if (const ElaboratedType *ET = dyn_cast<ElaboratedType>(QT))
+    QT = ET->getNamedType();
+
+  // Get the type's declaration.
+  NamedDecl *D = nullptr;
+  if (auto *TDT = dyn_cast<TypedefType>(QT))
+    D = TDT->getDecl();
+  else if (auto *UT = dyn_cast<UsingType>(QT))
+    D = UT->getFoundDecl();
+  else if (auto *TD = QT->getAsTagDecl())
+    return TD;
+  else if (auto *TT = dyn_cast<TagType>(QT))
+    D = TT->getDecl();
+  else if (auto *UUTD = dyn_cast<UnresolvedUsingType>(QT))
+    D = UUTD->getDecl();
+  else if (auto *TS = dyn_cast<TemplateSpecializationType>(QT)) {
+    if (auto *CTD = dyn_cast<ClassTemplateDecl>(
+          TS->getTemplateName().getAsTemplateDecl())) {
+      void *InsertPos;
+      D = CTD->findSpecialization(TS->template_arguments(), InsertPos);
+    }
+  } else if (auto *STTP = dyn_cast<SubstTemplateTypeParmType>(QT))
+    D = findTypeDecl(STTP->getReplacementType());
+  else if (auto *ICNT = dyn_cast<InjectedClassNameType>(QT))
+    D = ICNT->getDecl();
+  else if (auto *DTT = dyn_cast<DecltypeType>(QT))
+    D = findTypeDecl(DTT->getUnderlyingType());
+
+  return D;
+}
+
+// FIXME this is get_attributes, repeated here
+//
+bool Parser::tryParseSpliceAttrSpecifier(ParsedAttributes &Attrs,
+                                         SourceLocation *EndLoc)
+{
+  // Try parsing a [: meta-info :] immediately following '[' '['
+  if (!Tok.is(tok::l_splice)) {
+    return true;
+  }
+  if (ParseCXXSpliceSpecifier()) {
+    // FIXME diagnostic is terrible...
+    Diag(Tok.getLocation(), diag::p3385_err_attribute_splicing_error)
+        << "invalid expression in attribute splicing";
+    return true; // yea...Dont know what kind of convention that is
+  }
+  if (!Tok.is(tok::annot_splice)) {
+    return true;
+  }
+  Diag(Tok.getLocation(), diag::p3385_trace_execution_checkpoint)
+        << "Found splice in attribute expression";
+  SourceLocation loc = (Tok.getLocation());
+  SourceRange range(loc);
+
+  // FIXME What's this doing ?
+  ExprResult Result = getExprAnnotation(Tok);
+  ConsumeAnnotationToken();
+
+  // TODO export to ActOnBlablabla() is the `iDiOmAtIc WaY`
+  //
+  auto *SpliceExpr = cast<CXXSpliceSpecifierExpr>(Result.get());
+  Expr::EvalResult ER;
+  if (!SpliceExpr->EvaluateAsRValue(ER, Actions.getASTContext(), true)) {
+    return false;
+  }
+
+  assert(ER.Val.getKind() == APValue::Reflection);
+  switch (ER.Val.getReflectionKind()) {
+    case ReflectionKind::Attribute: {
+      auto * attr = ER.Val.getReflectedAttribute();
+
+      Attrs.addNew(
+          const_cast<IdentifierInfo*>(attr->getAttrName()), // (C) Trust me bro
+          range,
+          nullptr, loc, nullptr, 0,
+          ParsedAttr::Form::CXX11());
+      break;
+    }
+    case ReflectionKind::Type: {
+      QualType qType = ER.Val.getReflectedType();
+      Decl *D = findTypeDecl(qType);
+      if (!D) {
+        // FIXME how would we end up here ?
+        Diag(Tok.getLocation(), diag::p3385_err_attribute_splicing_error)
+          << "Error while splicing type attributes inside a [[ ]]";
+      }
+      for (auto *const attr : D->attrs()) {
+        Attrs.addNew(
+          const_cast<IdentifierInfo*>(attr->getAttrName()), // (C) Trust me bro 2
+          range,
+          nullptr, loc, nullptr, 0,
+          ParsedAttr::Form::CXX11());
+      }
+      break;
+    }
+    default: 
+        Diag(Tok.getLocation(), diag::p3385_err_attribute_splicing_error)
+          << "unsupported kind in attribute splicing";
+  }
+
+  // FIXME this shouldnt be here... but we early quit ParseCXX11AttributeSpecifierInternal 
+  // Finish with consuming close ']' ']
+  SourceLocation CloseLoc = Tok.getLocation();
+  if (ExpectAndConsume(tok::r_square))
+    SkipUntil(tok::r_square);
+  else if (Tok.is(tok::r_square))
+    checkCompoundToken(CloseLoc, tok::r_square, CompoundToken::AttrEnd);
+  if (EndLoc)
+    *EndLoc = Tok.getLocation();
+  if (ExpectAndConsume(tok::r_square))
+    SkipUntil(tok::r_square);
+
+  return false;
+}
+
 /// Parse a C++11 or C23 attribute-specifier.
 ///
 /// [C++11] attribute-specifier:
 ///         '[' '[' attribute-list ']' ']'
 ///         alignment-specifier
+///         '[' '[' splice-name-qualifier ']' ']'
 ///
 /// [C++11] attribute-list:
 ///         attribute[opt]
@@ -5151,6 +5274,13 @@ void Parser::ParseCXX11AttributeSpecifierInternal(ParsedAttributes &Attrs,
     SourceLocation ScopeLoc, AttrLoc;
     IdentifierInfo *ScopeName = nullptr, *AttrName = nullptr;
 
+    // Try parsing a `[: :]` expression
+    if (!tryParseSpliceAttrSpecifier(Attrs, EndLoc)) {
+      // I'll forget in 10 minutes but... in clang convention, we end up here
+      // when we actually did succeed... so we quit parsing attributes here.
+      return;
+    }
+
     if (Tok.is(tok::equal) && getLangOpts().AnnotationAttributes) {
       // This is a C++2c annotation.
       if (CommonScopeName) {
diff --git a/clang/lib/Parse/ParseReflect.cpp b/clang/lib/Parse/ParseReflect.cpp
index f76bb6b1c7ee73..9b0de2401b5cd1 100644
--- a/clang/lib/Parse/ParseReflect.cpp
+++ b/clang/lib/Parse/ParseReflect.cpp
@@ -12,10 +12,12 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "clang/AST/Attr.h"
 #include "clang/Parse/ParseDiagnostic.h"
 #include "clang/Parse/Parser.h"
 #include "clang/Parse/RAIIObjectsForParser.h"
 #include "clang/Sema/EnterExpressionEvaluationContext.h"
+#include "clang/Sema/Ownership.h"
 using namespace clang;
 
 ExprResult Parser::ParseCXXReflectExpression(SourceLocation OpLoc) {
@@ -79,6 +81,27 @@ ExprResult Parser::ParseCXXReflectExpression(SourceLocation OpLoc) {
   }
   TentativeAction.Revert();
 
+  // Check for a standard attribute
+  {
+    size_t last = Attrs.size();
+    if (MaybeParseCXX11Attributes(Attrs)) {
+      size_t newLast = Attrs.size();
+      Diag(OperandLoc, diag::p3385_trace_attribute_parsed);
+
+      // FIXME handle empty [[]] gracefully
+      if (last == newLast) {
+        Diag(OperandLoc, diag::p3385_trace_empty_attributes_list);
+        return ExprError();
+      }
+      if (newLast - last > 1) {
+        Diag(OperandLoc, diag::p3385_err_attributes_list) << (newLast - last);
+        return ExprError();
+      }
+
+      return Actions.ActOnCXXReflectExpr(OpLoc, &Attrs.back());
+    }
+  }
+
   if (SS.isSet() &&
       TryAnnotateTypeOrScopeTokenAfterScopeSpec(SS, true,
                                                 ImplicitTypenameContext::No)) {
diff --git a/clang/lib/Parse/Parser.cpp b/clang/lib/Parse/Parser.cpp
index 7f7851cc451536..4e1bd266bd24f2 100644
--- a/clang/lib/Parse/Parser.cpp
+++ b/clang/lib/Parse/Parser.cpp
@@ -21,6 +21,7 @@
 #include "clang/Parse/ParseDiagnostic.h"
 #include "clang/Parse/RAIIObjectsForParser.h"
 #include "clang/Sema/DeclSpec.h"
+#include "clang/Sema/ParsedAttr.h"
 #include "clang/Sema/ParsedTemplate.h"
 #include "clang/Sema/Scope.h"
 #include "clang/Sema/SemaCodeCompletion.h"
@@ -57,7 +58,7 @@ Parser::Parser(Preprocessor &pp, Sema &actions, bool skipFunctionBodies)
     : PP(pp), PreferredType(pp.isCodeCompletionEnabled()), Actions(actions),
       Diags(PP.getDiagnostics()), GreaterThanIsOperator(true),
       ColonIsSacred(false), InMessageExpression(false),
-      TemplateParameterDepth(0), ParsingInObjCContainer(false) {
+      TemplateParameterDepth(0), Attrs(AttrFactory), ParsingInObjCContainer(false) {
   SkipFunctionBodies = pp.isCodeCompletionEnabled() || skipFunctionBodies;
   Tok.startToken();
   Tok.setKind(tok::eof);
diff --git a/clang/lib/Sema/SemaReflect.cpp b/clang/lib/Sema/SemaReflect.cpp
index 15ccf9cf6396fd..2cd76dc0a8d57f 100644
--- a/clang/lib/Sema/SemaReflect.cpp
+++ b/clang/lib/Sema/SemaReflect.cpp
@@ -21,6 +21,7 @@
 #include "clang/Basic/DiagnosticSema.h"
 #include "clang/Sema/EnterExpressionEvaluationContext.h"
 #include "clang/Sema/Lookup.h"
+#include "clang/Sema/Ownership.h"
 #include "clang/Sema/ParsedTemplate.h"
 #include "clang/Sema/Sema.h"
 #include "clang/Sema/Template.h"
@@ -741,6 +742,11 @@ ExprResult Sema::ActOnCXXReflectExpr(SourceLocation OperatorLoc,
   return BuildCXXReflectExpr(OperatorLoc, E);
 }
 
+ExprResult Sema::ActOnCXXReflectExpr(SourceLocation OperatorLoc,
+                                     ParsedAttr *A) {
+  return BuildCXXReflectExpr(OperatorLoc, A);
+}
+
 /// Returns an expression representing the result of a metafunction operating
 /// on a reflection.
 ExprResult Sema::ActOnCXXMetafunction(SourceLocation KwLoc,
@@ -955,6 +961,10 @@ ParsedTemplateArgument Sema::ActOnTemplateSpliceSpecifierArgument(
     Diag(Splice->getExprLoc(), diag::err_unsupported_splice_kind)
       << "data member specs" << 0 << 0;
     break;
+  case ReflectionKind::Attribute:
+    Diag(Splice->getExprLoc(), diag::err_unsupported_splice_kind)
+      << "attribute" << 0 << 0;
+    break;
   }
   return ParsedTemplateArgument();
 }
@@ -1127,6 +1137,16 @@ ExprResult Sema::BuildCXXReflectExpr(SourceLocation OperatorLoc,
                                 ER.Val);
 }
 
+ExprResult Sema::BuildCXXReflectExpr(SourceLocation OperatorLoc,
+                                     ParsedAttr *A) {
+  Diag(A->getLoc(), diag::p3385_trace_building_attribute_reflection)
+      << A->getAttrName()->getName();
+
+  return CXXReflectExpr::Create(
+      Context, OperatorLoc, A->getRange(),
+      APValue{ReflectionKind::Attribute, static_cast<void *>(A)});
+}
+
 ExprResult Sema::BuildCXXMetafunctionExpr(
       SourceLocation KwLoc, SourceLocation LParenLoc, SourceLocation RParenLoc,
       unsigned MetaFnID, const CXXMetafunctionExpr::ImplFn &Impl,
@@ -1481,6 +1501,7 @@ ExprResult Sema::BuildReflectionSpliceExpr(
     case ReflectionKind::BaseSpecifier:
     case ReflectionKind::DataMemberSpec:
     case ReflectionKind::Annotation:
+    case ReflectionKind::Attribute:
       Diag(SpliceOp->getOperand()->getExprLoc(),
            diag::err_unexpected_reflection_kind_in_splice)
           << 1 << SpliceOp->getOperand()->getSourceRange();
@@ -1609,6 +1630,7 @@ DeclContext *Sema::TryFindDeclContextOf(const Expr *E) {
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     Diag(E->getExprLoc(), diag::err_expected_class_or_namespace)
         << "spliced entity" << getLangOpts().CPlusPlus;
     return nullptr;
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 6c38df3143e7dd..5be1edf0490651 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -8968,6 +8968,7 @@ TreeTransform<Derived>::TransformCXXReflectExpr(CXXReflectExpr *E) {
   case ReflectionKind::BaseSpecifier:
   case ReflectionKind::DataMemberSpec:
   case ReflectionKind::Annotation:
+  case ReflectionKind::Attribute:
     llvm_unreachable("reflect expression should not have this reflection kind");
   }
   llvm_unreachable("invalid reflection");
diff --git a/libcxx/include/experimental/meta b/libcxx/include/experimental/meta
index 1a1b322cc88d24..a4c5f78ff37991 100644
--- a/libcxx/include/experimental/meta
+++ b/libcxx/include/experimental/meta
@@ -381,6 +381,10 @@ template <typename T>
 consteval auto is_annotation(info) -> bool;
 consteval auto annotate(info) -> info;
 
+// Attributes reflection (P3385)
+consteval auto is_attribute(info) -> bool;
+consteval auto attributes_of(info r) -> vector<info>;
+
 } // namespace reflection_v2
 } // namespace meta
 } // namespace std
@@ -538,6 +542,10 @@ enum : unsigned {
   __metafn_get_ith_annotation_of,
   __metafn_is_annotation,
   __metafn_annotate,
+
+  // P3385 attributes reflection
+  __metafn_get_ith_attribute_of,
+  __metafn_is_attribute,
 };
 
 consteval auto __workaround_expand_compiler_builtins(info type) -> info;
@@ -748,6 +756,25 @@ struct front_annotation_of {
   }
 };
 
+// TODO #ifdef P3385 feature flag
+
+struct front_attribute_of {
+  consteval info operator()(info reflectedEntity) const {
+    return __metafunction(detail::__metafn_get_ith_attribute_of,
+                          reflectedEntity, LIFT(sentinel), 0);
+  }
+};
+
+struct next_attribute_of {
+  consteval info operator()(auto /*currItrInfo */, info reflectedEntity,
+                            size_t idx) const {
+    return __metafunction(detail::__metafn_get_ith_attribute_of,
+                          reflectedEntity, LIFT(sentinel), idx);
+  }
+};
+
+// TODO #endif P3385 feature flag
+
 }  // namespace __range_of_infos
 
 // -----------------------------------------------------------------------------
@@ -2174,6 +2201,24 @@ consteval auto annotate(info entity, info val) -> info {
 
 #endif  // __has_feature(annotation_attributes)
 
+// #ifdef TODO Feature flag for P3385
+
+// Returns whether the reflected entity is an attribute.
+consteval auto is_attribute(info r) -> bool {
+  return __metafunction(detail::__metafn_is_attribute, r);
+}
+
+consteval auto attributes_of(info r) -> vector<info> {
+  using iterator =
+  __range_of_infos::iterator<__range_of_infos::front_attribute_of,
+                             __range_of_infos::next_attribute_of,
+                             __range_of_infos::map_identity_fn>;
+  using range = __range_of_infos::range<iterator>;
+  auto rng = range{r};
+  return vector<info>{rng.begin(), rng.end()};
+}
+
+// #endif TODO Feature flag for P3385
 
 template <typename Ty>
 [[deprecated("separated into 'reflect_value', 'reflect_result', and "