diff --git a/include/swift/AST/Decl.h b/include/swift/AST/Decl.h
index 7b51c375b1e..61953727283 100644
--- a/include/swift/AST/Decl.h
+++ b/include/swift/AST/Decl.h
@@ -3095,6 +3095,9 @@ public:
   /// isGetterOrSetter - Determine whether this is a getter or a setter vs.
   /// a normal function.
   bool isGetterOrSetter() const { return isGetter() || isSetter(); }
+  bool isDidSetWillSet() const {
+    return getAccessorKind() == IsDidSet || getAccessorKind() == IsWillSet;
+  }
   bool isAccessor() const { return getAccessorKind() != NotAccessor; }
 
   /// Creates the implicit 'DynamicSelf' generic parameter.
diff --git a/lib/IRGen/ClassMetadataLayout.h b/lib/IRGen/ClassMetadataLayout.h
index 360b3db8050..3749193c953 100644
--- a/lib/IRGen/ClassMetadataLayout.h
+++ b/lib/IRGen/ClassMetadataLayout.h
@@ -210,7 +210,7 @@ private:
   void maybeAddMethod(FuncDecl *fn, ResilienceExpansion explosionLevel,
                       unsigned uncurryLevel) {
     // Ignore getters and setters.  This is probably wrong!
-    if (fn->isGetterOrSetter())
+    if (fn->isAccessor())
       return;
 
     // If the method overrides something, we don't need a new entry.
diff --git a/lib/IRGen/GenClass.cpp b/lib/IRGen/GenClass.cpp
index 5f129a9c88a..5e7f8225eed 100644
--- a/lib/IRGen/GenClass.cpp
+++ b/lib/IRGen/GenClass.cpp
@@ -1083,7 +1083,7 @@ namespace {
       
       // getters and setters funcdecls will be handled by their parent
       // var/subscript.
-      if (method->isGetterOrSetter()) return;
+      if (method->isAccessor()) return;
       
       llvm::Constant *entry = emitObjCMethodDescriptor(IGM, method);
       if (!method->isStatic()) {
diff --git a/lib/IRGen/GenObjC.cpp b/lib/IRGen/GenObjC.cpp
index c09f1275970..12c12cdc522 100644
--- a/lib/IRGen/GenObjC.cpp
+++ b/lib/IRGen/GenObjC.cpp
@@ -1171,7 +1171,7 @@ irgen::emitObjCSubscriptMethodDescriptors(IRGenModule &IGM,
 
 bool irgen::requiresObjCMethodDescriptor(FuncDecl *method) {
   // Property accessors should be generated alongside the property.
-  if (method->isGetterOrSetter())
+  if (method->isAccessor())
     return false;
     
     // We don't export generic methods or subclasses to IRGen yet.
diff --git a/lib/IRGen/GenProto.cpp b/lib/IRGen/GenProto.cpp
index b0c46ada865..9e018ef2e97 100644
--- a/lib/IRGen/GenProto.cpp
+++ b/lib/IRGen/GenProto.cpp
@@ -243,7 +243,7 @@ namespace {
     }
 
     void visitFunc(FuncDecl *func) {
-      if (func->isGetterOrSetter())
+      if (func->isAccessor())
         // FIXME: To be implemented.
         return;
       
diff --git a/lib/IRGen/IRGenDebugInfo.cpp b/lib/IRGen/IRGenDebugInfo.cpp
index c4d6eda98aa..b26e36fbcc7 100644
--- a/lib/IRGen/IRGenDebugInfo.cpp
+++ b/lib/IRGen/IRGenDebugInfo.cpp
@@ -366,11 +366,19 @@ llvm::DIFile IRGenDebugInfo::getOrCreateFile(const char *Filename) {
 StringRef IRGenDebugInfo::getName(const FuncDecl &FD) {
   // Getters and Setters are anonymous functions, so we forge a name
   // using its parent declaration.
-  if (FD.isGetterOrSetter())
+  if (FD.isAccessor())
     if (ValueDecl *VD = FD.getAccessorStorageDecl()) {
+      const char *Kind;
+      switch (FD.getAccessorKind()) {
+      case FuncDecl::NotAccessor: assert(0 && "we know this is an accessor");
+      case FuncDecl::IsGetter: Kind = ".get"; break;
+      case FuncDecl::IsSetter: Kind = ".set"; break;
+      case FuncDecl::IsWillSet: Kind = ".willset"; break;
+      case FuncDecl::IsDidSet: Kind = ".didset"; break;
+      }
+      
       SmallVector<char, 64> Buf;
-      StringRef Name = (VD->getName().str() +
-                        Twine(FD.isGetter() ? ".get":".set")).toStringRef(Buf);
+      StringRef Name = (VD->getName().str() +Twine(Kind)).toStringRef(Buf);
       return BumpAllocatedString(Name);
     }
 
diff --git a/lib/SILGen/SILGenApply.cpp b/lib/SILGen/SILGenApply.cpp
index f0e76e684ae..4378323514f 100644
--- a/lib/SILGen/SILGenApply.cpp
+++ b/lib/SILGen/SILGenApply.cpp
@@ -800,7 +800,10 @@ public:
     // FIXME: Or if it's an ObjC method. Extension methods on classes will
     // hopefully become dynamically dispatched too.
     if (auto *fd = dyn_cast<FuncDecl>(e->getDecl())) {
-      if (isa<ClassDecl>(fd->getDeclContext()) || fd->isObjC()) {
+      if (fd->isObjC() ||
+          (isa<ClassDecl>(fd->getDeclContext()) &&
+           // didSet and willSet methods can always be directly dispatched.
+           !fd->isDidSetWillSet())) {
         ApplyExpr *thisCallSite = callSites.back();
         callSites.pop_back();
         setSelfParam(gen.emitRValue(thisCallSite->getArg()), thisCallSite);