Index: llvm/trunk/lib/CodeGen/GlobalMerge.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/GlobalMerge.cpp
+++ llvm/trunk/lib/CodeGen/GlobalMerge.cpp
@@ -445,6 +445,7 @@
   LLVM_DEBUG(dbgs() << " Trying to merge set, starts with #"
                     << GlobalSet.find_first() << "\n");
 
+  bool Changed = false;
   ssize_t i = GlobalSet.find_first();
   while (i != -1) {
     ssize_t j = 0;
@@ -469,6 +470,12 @@
       }
     }
 
+    // Exit early if there is only one global to merge.
+    if (Tys.size() < 2) {
+      i = j;
+      continue;
+    }
+
     // If merged variables doesn't have external linkage, we needn't to expose
     // the symbol after merging.
     GlobalValue::LinkageTypes Linkage = HasExternal
@@ -526,10 +533,11 @@
 
       NumMerged++;
     }
+    Changed = true;
     i = j;
   }
 
-  return true;
+  return Changed;
 }
 
 void GlobalMerge::collectUsedGlobalVariables(Module &M) {
Index: llvm/trunk/test/CodeGen/AArch64/global-merge-3.ll
===================================================================
--- llvm/trunk/test/CodeGen/AArch64/global-merge-3.ll
+++ llvm/trunk/test/CodeGen/AArch64/global-merge-3.ll
@@ -10,8 +10,8 @@
 ;CHECK-APPLE-IOS: adrp	x8, __MergedGlobals_x@PAGE
 ;CHECK-APPLE-IOS-NOT: adrp
 ;CHECK-APPLE-IOS: add	x8, x8, __MergedGlobals_x@PAGEOFF
-;CHECK-APPLE-IOS: adrp	x9, __MergedGlobals_y@PAGE+12
-;CHECK-APPLE-IOS: str	w1, [x9, __MergedGlobals_y@PAGEOFF+12]
+;CHECK-APPLE-IOS: adrp	x9, _y@PAGE+12
+;CHECK-APPLE-IOS: str	w1, [x9]
   %x3 = getelementptr inbounds [1000 x i32], [1000 x i32]* @x, i32 0, i64 3
   %y3 = getelementptr inbounds [1000 x i32], [1000 x i32]* @y, i32 0, i64 3
   store i32 %a1, i32* %x3, align 4
@@ -25,27 +25,19 @@
 ;CHECK: .L_MergedGlobals:
 ;CHECK: .size	.L_MergedGlobals, 4004
 
-;CHECK: .type	.L_MergedGlobals.1,@object // @_MergedGlobals.1
-;CHECK: .local	.L_MergedGlobals.1
-;CHECK: .comm	.L_MergedGlobals.1,4000,16
+;CHECK-APPLE-IOS: .zerofill __DATA,__common,_y,4000,2
 
 ;CHECK-APPLE-IOS: .p2align	4
 ;CHECK-APPLE-IOS:  __MergedGlobals_x:
 ;CHECK-APPLE-IOS: .long 1
 ;CHECK-APPLE-IOS: .space	4000
 
-;CHECK-APPLE-IOS: .zerofill __DATA,__common,__MergedGlobals_y,4000,4
 
 ;CHECK: .set z, .L_MergedGlobals
 ;CHECK:	.globl	x
 ;CHECK: .set x, .L_MergedGlobals+4
 ;CHECK: .size x, 4000
-;CHECK:	.globl	y
-;CHECK: .set y, .L_MergedGlobals.1
-;CHECK: .size y, 4000
 
 ;CHECK-APPLE-IOS-NOT: .set _z, __MergedGlobals_x
 ;CHECK-APPLE-IOS:.globl	_x
 ;CHECK-APPLE-IOS:.set _x, __MergedGlobals_x+4
-;CHECK-APPLE-IOS:.globl	_y
-;CHECK-APPLE-IOS:.set _y, __MergedGlobals_y
Index: llvm/trunk/test/CodeGen/ARM/global-merge.ll
===================================================================
--- llvm/trunk/test/CodeGen/ARM/global-merge.ll
+++ llvm/trunk/test/CodeGen/ARM/global-merge.ll
@@ -52,23 +52,23 @@
 
 declare void @__cxa_end_catch()
 
+; CHECK: g3:
 ; CHECK: _MergedGlobals:
 @g1 = internal global i32 1
 @g2 = internal global i32 2
 
 ; Make sure that the complete variable fits within the range of the maximum
 ; offset.  Having the starting offset in range is not sufficient.
-; When this works properly, @g3 is placed in a separate chunk of merged globals.
-; CHECK: _MergedGlobals.1:
+; When this works properly, @g3 is not merged.
 @g3 = internal global [30 x i32] [ i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 9, i32 10, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 9, i32 10, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 9, i32 10 ], align 4
 
 ; Global variables that can be placed in BSS should be kept together in a
 ; separate pool of merged globals.
-; CHECK: _MergedGlobals.2
+; CHECK: _MergedGlobals.1
 @g4 = internal global i32 0
 @g5 = internal global i32 0
 
 ; Global variables that are constant can be merged together
-; CHECK: _MergedGlobals.3
+; CHECK: _MergedGlobals.2
 @g6 = internal constant [12 x i32] zeroinitializer, align 4
 @g7 = internal constant [12 x i32] zeroinitializer, align 4