diff --git a/lib/Sema/SemaTemplateInstantiateDecl.cpp b/lib/Sema/SemaTemplateInstantiateDecl.cpp
index e3b6614..1c7869f 100644
--- a/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -2274,6 +2274,11 @@
        Inits != InitsEnd; ++Inits) {
     CXXBaseOrMemberInitializer *Init = *Inits;
 
+    // Only instantiate written initializers, let Sema re-construct implicit
+    // ones.
+    if (!Init->isWritten())
+      continue;
+
     SourceLocation LParenLoc, RParenLoc;
     ASTOwningVector<Expr*> NewArgs(*this);
     llvm::SmallVector<SourceLocation, 4> CommaLocs;