Index: lib/Linker/LinkModules.cpp
===================================================================
--- lib/Linker/LinkModules.cpp
+++ lib/Linker/LinkModules.cpp
@@ -1026,6 +1026,12 @@
     if (NewGV != DGV)
       copyGVAttributes(NewGV, SGV);
 
+    // Don't unset unnamed_addr on values with a jumptable attribute, since that
+    // leads to an invalid module.
+    if (Function *NewGVF = dyn_cast<Function>(NewGV))
+      if (NewGVF->hasFnAttribute(Attribute::JumpTable))
+        HasUnnamedAddr = true;
+
     NewGV->setUnnamedAddr(HasUnnamedAddr);
     NewGV->setVisibility(Visibility);
 
Index: test/Linker/jumptable-a.ll
===================================================================
--- /dev/null
+++ test/Linker/jumptable-a.ll
@@ -0,0 +1,4 @@
+; RUN: llvm-link %s %p/jumptable-b.ll -S -o - | FileCheck %s
+declare void @f()
+; CHECK: ; Function Attrs: jumptable
+; CHECK: define void @f() unnamed_addr #0 {
Index: test/Linker/jumptable-b.ll
===================================================================
--- /dev/null
+++ test/Linker/jumptable-b.ll
@@ -0,0 +1,4 @@
+; RUN: true
+define void @f() unnamed_addr jumptable {
+  ret void
+}