diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index c1a6c60..67493c7 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -2229,6 +2229,20 @@
            << DS.getSourceRange();
   }
 
+  if (DS.isConstexprSpecified()) {
+    // C++0x [dcl.constexpr]p1: constexpr can only be applied to declarations
+    // and definitions of functions and variables.
+    if (Tag)
+      Diag(DS.getConstexprSpecLoc(), diag::err_constexpr_tag)
+        << (DS.getTypeSpecType() == DeclSpec::TST_class ? 0 :
+            DS.getTypeSpecType() == DeclSpec::TST_struct ? 1 :
+            DS.getTypeSpecType() == DeclSpec::TST_union ? 2 : 3);
+    else
+      Diag(DS.getConstexprSpecLoc(), diag::err_constexpr_no_declarators);
+    // Don't emit warnings after this error.
+    return TagD;
+  }
+
   if (DS.isFriendSpecified()) {
     // If we're dealing with a decl but not a TagDecl, assume that
     // whatever routines created it handled the friendship aspect.
@@ -3434,6 +3448,9 @@
 
   if (D.getDeclSpec().isThreadSpecified())
     Diag(D.getDeclSpec().getThreadSpecLoc(), diag::err_invalid_thread);
+  if (D.getDeclSpec().isConstexprSpecified())
+    Diag(D.getDeclSpec().getConstexprSpecLoc(), diag::err_invalid_constexpr)
+      << 1;
 
   if (D.getName().Kind != UnqualifiedId::IK_Identifier) {
     Diag(D.getName().StartLocation, diag::err_typedef_not_identifier)
@@ -3767,6 +3784,11 @@
                                            TemplateParamLists.size(),
                                            TemplateParamLists.release());
     }
+
+    if (D.getDeclSpec().isConstexprSpecified()) {
+      // FIXME: check this is a valid use of constexpr.
+      NewVD->setConstexpr(true);
+    }
   }
 
   if (D.getDeclSpec().isThreadSpecified()) {
@@ -4304,6 +4326,7 @@
     isFriend = D.getDeclSpec().isFriendSpecified();
     bool isVirtual = D.getDeclSpec().isVirtualSpecified();
     bool isExplicit = D.getDeclSpec().isExplicitSpecified();
+    bool isConstexpr = D.getDeclSpec().isConstexprSpecified();
     bool isVirtualOkay = false;
 
     // Check that the return type is not an abstract class type.
@@ -4330,7 +4353,8 @@
                                          D.getSourceRange().getBegin(),
                                          NameInfo, R, TInfo,
                                          isExplicit, isInline,
-                                         /*isImplicitlyDeclared=*/false);
+                                         /*isImplicitlyDeclared=*/false,
+                                         isConstexpr);
 
       NewFD = NewCD;
     } else if (Name.getNameKind() == DeclarationName::CXXDestructorName) {
@@ -4364,7 +4388,7 @@
         NewFD = FunctionDecl::Create(Context, DC, D.getSourceRange().getBegin(),
                                      D.getIdentifierLoc(), Name, R, TInfo,
                                      SC, SCAsWritten, isInline,
-                                     /*hasPrototype=*/true);
+                                     /*hasPrototype=*/true, isConstexpr);
         D.setInvalidType();
       }
     } else if (Name.getNameKind() == DeclarationName::CXXConversionFunctionName) {
@@ -4378,7 +4402,7 @@
       NewFD = CXXConversionDecl::Create(Context, cast<CXXRecordDecl>(DC),
                                         D.getSourceRange().getBegin(),
                                         NameInfo, R, TInfo,
-                                        isInline, isExplicit,
+                                        isInline, isExplicit, isConstexpr,
                                         SourceLocation());
 
       isVirtualOkay = true;
@@ -4416,6 +4440,7 @@
                                                D.getSourceRange().getBegin(),
                                                NameInfo, R, TInfo,
                                                isStatic, SCAsWritten, isInline,
+                                               isConstexpr,
                                                SourceLocation());
       NewFD = NewMD;
 
@@ -4426,7 +4451,7 @@
       //   - we're in C++ (where every function has a prototype),
       NewFD = FunctionDecl::Create(Context, DC, D.getSourceRange().getBegin(),
                                    NameInfo, R, TInfo, SC, SCAsWritten, isInline,
-                                   true/*HasPrototype*/);
+                                   true/*HasPrototype*/, isConstexpr);
     }
 
     if (isFriend && !isInline && IsFunctionDefinition) {
@@ -4590,6 +4615,23 @@
       }      
     }
 
+    if (isConstexpr) {
+      // C++0x [dcl.constexpr]p2: constexpr functions and constexpr constructors
+      // are implicitly inline.
+      NewFD->setImplicitlyInline();
+
+      // FIXME: If this is a redeclaration, check the original declaration was
+      // marked constepr.
+
+      // C++0x [dcl.constexpr]p3: functions declared constexpr are required to
+      // be either constructors or to return a literal type. Therefore,
+      // destructors cannot be declared constexpr.
+      if (isa<CXXDestructorDecl>(NewFD))
+        Diag(D.getDeclSpec().getConstexprSpecLoc(),
+             diag::err_constexpr_dtor);
+    }
+
+
     // Filter out previous declarations that don't match the scope.
     FilterLookupForScope(Previous, DC, S, NewFD->hasLinkage(),
                          isExplicitSpecialization || 
@@ -6105,6 +6147,9 @@
 
   if (D.getDeclSpec().isThreadSpecified())
     Diag(D.getDeclSpec().getThreadSpecLoc(), diag::err_invalid_thread);
+  if (D.getDeclSpec().isConstexprSpecified())
+    Diag(D.getDeclSpec().getConstexprSpecLoc(), diag::err_invalid_constexpr)
+      << 0;
 
   DiagnoseFunctionSpecifiers(D);
 
@@ -7813,6 +7858,9 @@
 
   if (D.getDeclSpec().isThreadSpecified())
     Diag(D.getDeclSpec().getThreadSpecLoc(), diag::err_invalid_thread);
+  if (D.getDeclSpec().isConstexprSpecified())
+    Diag(D.getDeclSpec().getConstexprSpecLoc(), diag::err_invalid_constexpr)
+      << 2;
   
   // Check to see if this name was declared as a member previously
   LookupResult Previous(*this, II, Loc, LookupMemberName, ForRedeclaration);
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index 76461a0..4283162 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -6012,7 +6012,9 @@
                                  /*TInfo=*/0,
                                  /*isExplicit=*/false,
                                  /*isInline=*/true,
-                                 /*isImplicitlyDeclared=*/true);
+                                 /*isImplicitlyDeclared=*/true,
+                                 // FIXME: apply the rules for definitions here
+                                 /*isConstexpr=*/false);
   DefaultCon->setAccess(AS_public);
   DefaultCon->setDefaulted();
   DefaultCon->setImplicit();
@@ -6263,12 +6265,15 @@
 
         // OK, we're there, now add the constructor.
         // C++0x [class.inhctor]p8: [...] that would be performed by a
-        //   user-writtern inline constructor [...]
+        //   user-written inline constructor [...]
         DeclarationNameInfo DNI(CreatedCtorName, UsingLoc);
         CXXConstructorDecl *NewCtor = CXXConstructorDecl::Create(
             Context, ClassDecl, UsingLoc, DNI, QualType(NewCtorType, 0),
             /*TInfo=*/0, BaseCtor->isExplicit(), /*Inline=*/true,
-            /*ImplicitlyDeclared=*/true);
+            /*ImplicitlyDeclared=*/true,
+            // FIXME: Due to a defect in the standard, we treat inherited
+            // constructors as constexpr even if that makes them ill-formed.
+            /*Constexpr=*/BaseCtor->isConstexpr());
         NewCtor->setAccess(BaseCtor->getAccess());
 
         // Build up the parameter decls and add them.
@@ -6777,7 +6782,7 @@
                             Context.getFunctionType(RetType, &ArgType, 1, EPI),
                             /*TInfo=*/0, /*isStatic=*/false,
                             /*StorageClassAsWritten=*/SC_None,
-                            /*isInline=*/true,
+                            /*isInline=*/true, /*isConstexpr=*/false,
                             SourceLocation());
   CopyAssignment->setAccess(AS_public);
   CopyAssignment->setDefaulted();
@@ -7249,7 +7254,9 @@
                                  /*TInfo=*/0,
                                  /*isExplicit=*/false,
                                  /*isInline=*/true,
-                                 /*isImplicitlyDeclared=*/true);
+                                 /*isImplicitlyDeclared=*/true,
+                                 // FIXME: apply the rules for definitions here
+                                 /*isConstexpr=*/false);
   CopyConstructor->setAccess(AS_public);
   CopyConstructor->setDefaulted();
   CopyConstructor->setTrivial(ClassDecl->hasTrivialCopyConstructor());
diff --git a/lib/Sema/SemaTemplateInstantiateDecl.cpp b/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 2554b82..812482e 100644
--- a/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -1070,11 +1070,15 @@
                                          TemplateArgs);
   }
 
+  bool isConstexpr = D->isConstexpr();
+  // FIXME: check whether the instantiation produces a constexpr function.
+
   FunctionDecl *Function =
       FunctionDecl::Create(SemaRef.Context, DC, D->getInnerLocStart(),
                            D->getLocation(), D->getDeclName(), T, TInfo,
                            D->getStorageClass(), D->getStorageClassAsWritten(),
-                           D->isInlineSpecified(), D->hasWrittenPrototype());
+                           D->isInlineSpecified(), D->hasWrittenPrototype(),
+                           isConstexpr);
 
   if (QualifierLoc)
     Function->setQualifierInfo(QualifierLoc);
@@ -1383,6 +1387,9 @@
     if (!DC) return 0;
   }
 
+  bool isConstexpr = D->isConstexpr();
+  // FIXME: check whether the instantiation produces a constexpr function.
+
   // Build the instantiated method declaration.
   CXXRecordDecl *Record = cast<CXXRecordDecl>(DC);
   CXXMethodDecl *Method = 0;
@@ -1395,7 +1402,7 @@
                                         StartLoc, NameInfo, T, TInfo,
                                         Constructor->isExplicit(),
                                         Constructor->isInlineSpecified(),
-                                        false);
+                                        false, isConstexpr);
   } else if (CXXDestructorDecl *Destructor = dyn_cast<CXXDestructorDecl>(D)) {
     Method = CXXDestructorDecl::Create(SemaRef.Context, Record,
                                        StartLoc, NameInfo, T, TInfo,
@@ -1406,14 +1413,14 @@
                                        StartLoc, NameInfo, T, TInfo,
                                        Conversion->isInlineSpecified(),
                                        Conversion->isExplicit(),
-                                       Conversion->getLocEnd());
+                                       isConstexpr, Conversion->getLocEnd());
   } else {
     Method = CXXMethodDecl::Create(SemaRef.Context, Record,
                                    StartLoc, NameInfo, T, TInfo,
                                    D->isStatic(),
                                    D->getStorageClassAsWritten(),
                                    D->isInlineSpecified(),
-                                   D->getLocEnd());
+                                   isConstexpr, D->getLocEnd());
   }
 
   if (QualifierLoc)