Index: lib/Transforms/IPO/ConstantMerge.cpp
===================================================================
--- lib/Transforms/IPO/ConstantMerge.cpp
+++ lib/Transforms/IPO/ConstantMerge.cpp
@@ -60,6 +60,12 @@
   return A.hasGlobalUnnamedAddr();
 }
 
+static bool hasTypeAnnotations(const GlobalVariable *GV) {
+  SmallVector<MDNode *, 2> Types;
+  GV->getMetadata(LLVMContext::MD_type, Types);
+  return !Types.empty();
+}
+
 static unsigned getAlignment(GlobalVariable *GV) {
   unsigned Align = GV->getAlignment();
   if (Align)
@@ -113,6 +119,12 @@
       if (GV->isWeakForLinker())
         continue;
 
+      // Don't touch globals with !type annotations. An alternative is to assign
+      // the merged global the union of all type annotations, but that can make
+      // type tests less precise and also slower.
+      if (hasTypeAnnotations(GV))
+        continue;
+
       Constant *Init = GV->getInitializer();
 
       // Check to see if the initializer is already known.
@@ -155,6 +167,9 @@
       if (!Slot->hasGlobalUnnamedAddr() && !GV->hasGlobalUnnamedAddr())
         continue;
 
+      if (hasTypeAnnotations(GV))
+        continue;
+
       if (!GV->hasGlobalUnnamedAddr())
         Slot->setUnnamedAddr(GlobalValue::UnnamedAddr::None);
 
Index: test/Transforms/ConstantMerge/dont-merge.ll
===================================================================
--- test/Transforms/ConstantMerge/dont-merge.ll
+++ test/Transforms/ConstantMerge/dont-merge.ll
@@ -42,3 +42,41 @@
   call void asm sideeffect "T3A, T3B",""() ; invisible use of T3A and T3B
   ret void
 }
+
+; Don't merge constants with !type annotations.
+
+@T4A1 = internal constant i32 2, !type !0
+@T4A2 = internal unnamed_addr constant i32 2, !type !1
+
+@T4B1 = internal constant i32 3, !type !0
+@T4B2 = internal unnamed_addr constant i32 3, !type !0
+
+@T4C1 = internal constant i32 4, !type !0
+@T4C2 = unnamed_addr constant i32 4
+
+@T4D1 = unnamed_addr constant i32 5, !type !0
+@T4D2 = internal constant i32 5
+
+!0 = !{i64 0, !"typeinfo name for A"}
+!1 = !{i64 0, !"typeinfo name for B"}
+
+; CHECK: @T4A1
+; CHECK: @T4A2
+; CHECK: @T4B1
+; CHECK: @T4B2
+; CHECK: @T4C1
+; CHECK: @T4C2
+; CHECK: @T4D1
+; CHECK: @T4D2
+
+define void @test4(i32** %P1, i32** %P2, i32** %P3, i32** %P4, i32** %P5, i32** %P6, i32** %P7, i32** %P8) {
+        store i32* @T4A1, i32** %P1
+        store i32* @T4A2, i32** %P2
+        store i32* @T4B1, i32** %P3
+        store i32* @T4B2, i32** %P4
+        store i32* @T4C1, i32** %P5
+        store i32* @T4C2, i32** %P6
+        store i32* @T4D1, i32** %P7
+        store i32* @T4D2, i32** %P8
+        ret void
+}