diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 9efcb52..d584ed8 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -6362,9 +6362,31 @@
       }
       
     } else {
-      if (isa<CXXMethodDecl>(NewFD)) // Set access for out-of-line definitions
-        NewFD->setAccess(OldDecl->getAccess());
+      // This needs to happen first so that 'inline' propagates.
       NewFD->setPreviousDeclaration(cast<FunctionDecl>(OldDecl));
+
+      if (isa<CXXMethodDecl>(NewFD)) {
+        // A valid redeclaration of a C++ method must be out-of-line,
+        // but (unfortunately) it's not necessarily a definition
+        // because of templates, which means that the previous
+        // declaration is not necessarily from the class definition.
+
+        // For just setting the access, that doesn't matter.
+        CXXMethodDecl *oldMethod = cast<CXXMethodDecl>(OldDecl);
+        NewFD->setAccess(oldMethod->getAccess());
+
+        // Update the key-function state if necessary for this ABI.
+        if (NewFD->isInlined() &&
+            !Context.getTargetInfo().getCXXABI().canKeyFunctionBeInline()) {
+          // setNonKeyFunction needs to work with the original
+          // declaration from the class definition, and isVirtual() is
+          // just faster in that case, so map back to that now.
+          oldMethod = cast<CXXMethodDecl>(oldMethod->getFirstDeclaration());
+          if (oldMethod->isVirtual()) {
+            Context.setNonKeyFunction(oldMethod);
+          }
+        }
+      }
     }
   }