diff --git a/lib/Sema/SemaTemplateInstantiateDecl.cpp b/lib/Sema/SemaTemplateInstantiateDecl.cpp
index cd08b1e..22db4c8 100644
--- a/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -2555,6 +2555,10 @@
         == TSK_ExplicitInstantiationDeclaration)
     return;
 
+  // If we already have a definition, we're done.
+  if (Var->getDefinition())
+    return;
+
   InstantiatingTemplate Inst(*this, PointOfInstantiation, Var);
   if (Inst)
     return;