Index: llvm/trunk/lib/Transforms/IPO/GlobalOpt.cpp
===================================================================
--- llvm/trunk/lib/Transforms/IPO/GlobalOpt.cpp
+++ llvm/trunk/lib/Transforms/IPO/GlobalOpt.cpp
@@ -497,6 +497,7 @@
                                                In, GV->getName()+"."+Twine(i),
                                                GV->getThreadLocalMode(),
                                               GV->getType()->getAddressSpace());
+      NGV->setExternallyInitialized(GV->isExternallyInitialized());
       Globals.insert(GV->getIterator(), NGV);
       NewGlobals.push_back(NGV);
 
@@ -530,6 +531,7 @@
                                                In, GV->getName()+"."+Twine(i),
                                                GV->getThreadLocalMode(),
                                               GV->getType()->getAddressSpace());
+      NGV->setExternallyInitialized(GV->isExternallyInitialized());
       Globals.insert(GV->getIterator(), NGV);
       NewGlobals.push_back(NGV);
 
Index: llvm/trunk/test/Transforms/GlobalOpt/externally-initialized-aggregate.ll
===================================================================
--- llvm/trunk/test/Transforms/GlobalOpt/externally-initialized-aggregate.ll
+++ llvm/trunk/test/Transforms/GlobalOpt/externally-initialized-aggregate.ll
@@ -0,0 +1,50 @@
+; RUN: opt < %s -S -globalopt | FileCheck %s
+
+; This global is externally_initialized, so if we split it into scalars we
+; should keep that flag set on all of the new globals. This will prevent the
+; store to @a[0] from being constant propagated to the load in @foo, but will not
+; prevent @a[1] from being removed since it is dead.
+; CHECK: @a.0 = internal unnamed_addr externally_initialized global i32 undef
+; CHECK-NOT @a.1
+@a = internal externally_initialized global [2 x i32] undef, align 4
+; This is the same, but a struct rather than an array.
+; CHECK: @b.0 = internal unnamed_addr externally_initialized global i32 undef
+; CHECK-NOT @b.1
+@b = internal externally_initialized global {i32, i32} undef, align 4
+
+define i32 @foo() {
+; CHECK-LABEL: define i32 @foo
+entry:
+; This load uses the split global, but cannot be constant-propagated away.
+; CHECK: %0 = load i32, i32* @a.0
+  %0 = load i32, i32* getelementptr inbounds ([2 x i32], [2 x i32]* @a, i32 0, i32 0), align 4
+  ret i32 %0
+}
+
+define i32 @bar() {
+; CHECK-LABEL: define i32 @bar
+entry:
+; This load uses the split global, but cannot be constant-propagated away.
+; CHECK: %0 = load i32, i32* @b.0
+  %0 = load i32, i32* getelementptr inbounds ({i32, i32}, {i32, i32}* @b, i32 0, i32 0), align 4
+  ret i32 %0
+}
+
+define void @init() {
+; CHECK-LABEL: define void @init
+entry:
+; This store uses the split global, but cannot be constant-propagated away.
+; CHECK: store i32 1, i32* @a.0
+  store i32 1, i32* getelementptr inbounds ([2 x i32], [2 x i32]* @a, i32 0, i32 0), align 4
+; This store can be removed, because the second element of @a is never read.
+; CHECK-NOT: store i32 2, i32* @a.1
+  store i32 2, i32* getelementptr inbounds ([2 x i32], [2 x i32]* @a, i32 0, i32 1), align 4
+
+; This store uses the split global, but cannot be constant-propagated away.
+; CHECK: store i32 3, i32* @b.0
+  store i32 3, i32* getelementptr inbounds ({i32, i32}, {i32, i32}* @b, i32 0, i32 0), align 4
+; This store can be removed, because the second element of @b is never read.
+; CHECK-NOT: store i32 4, i32* @b.1
+  store i32 4, i32* getelementptr inbounds ({i32, i32}, {i32, i32}* @b, i32 0, i32 1), align 4
+  ret void
+}