diff --git a/lib/AST/DeclBase.cpp b/lib/AST/DeclBase.cpp
index 10e6125..2e19265 100644
--- a/lib/AST/DeclBase.cpp
+++ b/lib/AST/DeclBase.cpp
@@ -69,7 +69,7 @@
 
 void Decl::setInvalidDecl(bool Invalid) {
   InvalidDecl = Invalid;
-  if (Invalid) {
+  if (Invalid && !isa<ParmVarDecl>(this)) {
     // Defensive maneuver for ill-formed code: we're likely not to make it to
     // a point where we set the access specifier, so default it to "public"
     // to avoid triggering asserts elsewhere in the front end. 
diff --git a/lib/Serialization/ASTWriterDecl.cpp b/lib/Serialization/ASTWriterDecl.cpp
index 1b576aa..d838e73 100644
--- a/lib/Serialization/ASTWriterDecl.cpp
+++ b/lib/Serialization/ASTWriterDecl.cpp
@@ -729,6 +729,7 @@
       !D->hasExtInfo() &&
       !D->isImplicit() &&
       !D->isUsed(false) &&
+      !D->isInvalidDecl() &&
       !D->isReferenced() &&
       D->getAccess() == AS_none &&
       !D->isModulePrivate() &&
@@ -744,7 +745,6 @@
 
   // Check things we know are true of *every* PARM_VAR_DECL, which is more than
   // just us assuming it.
-  assert(!D->isInvalidDecl() && "Shouldn't emit invalid decls");
   assert(!D->isThreadSpecified() && "PARM_VAR_DECL can't be __thread");
   assert(D->getAccess() == AS_none && "PARM_VAR_DECL can't be public/private");
   assert(!D->isExceptionVariable() && "PARM_VAR_DECL can't be exception var");
@@ -1267,7 +1267,7 @@
   // Decl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
-  Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl (!?)
+  Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl
   Abv->Add(BitCodeAbbrevOp(0));                       // HasAttrs
   Abv->Add(BitCodeAbbrevOp(0));                       // isImplicit
   Abv->Add(BitCodeAbbrevOp(0));                       // isUsed
@@ -1299,7 +1299,7 @@
   // Decl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
-  Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl (!?)
+  Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl
   Abv->Add(BitCodeAbbrevOp(0));                       // HasAttrs
   Abv->Add(BitCodeAbbrevOp(0));                       // isImplicit
   Abv->Add(BitCodeAbbrevOp(0));                       // isUsed
@@ -1336,7 +1336,7 @@
   // Decl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
-  Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl (!?)
+  Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl
   Abv->Add(BitCodeAbbrevOp(0));                       // HasAttrs
   Abv->Add(BitCodeAbbrevOp(0));                       // isImplicit
   Abv->Add(BitCodeAbbrevOp(0));                       // isUsed
@@ -1383,7 +1383,7 @@
   // Decl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
-  Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl (!?)
+  Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl
   Abv->Add(BitCodeAbbrevOp(0));                       // HasAttrs
   Abv->Add(BitCodeAbbrevOp(0));                       // isImplicit
   Abv->Add(BitCodeAbbrevOp(0));                       // isUsed
@@ -1424,7 +1424,7 @@
   // Decl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
-  Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl (!?)
+  Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl
   Abv->Add(BitCodeAbbrevOp(0));                       // HasAttrs
   Abv->Add(BitCodeAbbrevOp(0));                       // isImplicit
   Abv->Add(BitCodeAbbrevOp(0));                       // isUsed
@@ -1474,7 +1474,7 @@
   // Decl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
-  Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl (!?)
+  Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl
   Abv->Add(BitCodeAbbrevOp(0));                       // HasAttrs
   Abv->Add(BitCodeAbbrevOp(0));                       // isImplicit
   Abv->Add(BitCodeAbbrevOp(0));                       // isUsed
@@ -1502,7 +1502,7 @@
   // Decl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
-  Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl (!?)
+  Abv->Add(BitCodeAbbrevOp(0));                       // isInvalidDecl
   Abv->Add(BitCodeAbbrevOp(0));                       // HasAttrs
   Abv->Add(BitCodeAbbrevOp(0));                       // isImplicit
   Abv->Add(BitCodeAbbrevOp(0));                       // isUsed
diff --git a/test/Index/pch-with-errors.c b/test/Index/pch-with-errors.c
index 691eab4..be8728e 100644
--- a/test/Index/pch-with-errors.c
+++ b/test/Index/pch-with-errors.c
@@ -13,6 +13,8 @@
   zed h;
 };
 
+void errparm(zed e);
+
 struct S {
   {
 ;