diff --git a/lib/Target/ARM/ARMRegisterInfo.td b/lib/Target/ARM/ARMRegisterInfo.td
index 89ffed16b9f..77db711fb7b 100644
--- a/lib/Target/ARM/ARMRegisterInfo.td
+++ b/lib/Target/ARM/ARMRegisterInfo.td
@@ -160,6 +160,13 @@ def GPR : RegisterClass<"ARM", [i32], 32, [R0, R1, R2, R3, R4, R5, R6,
       ARM::R4, ARM::R5, ARM::R6,
       ARM::R8, ARM::R10,ARM::R11,
       ARM::R7 };
+    // FP is R7, R9 is available as callee-saved register.
+    // This is used by non-Darwin platform in Thumb mode.
+    static const unsigned ARM_GPR_AO_5[] = {
+      ARM::R0, ARM::R1, ARM::R2, ARM::R3,
+      ARM::R12,ARM::LR,
+      ARM::R4, ARM::R5, ARM::R6,
+      ARM::R8, ARM::R9, ARM::R10,ARM::R11,ARM::R7 };
 
     GPRClass::iterator
     GPRClass::allocation_order_begin(const MachineFunction &MF) const {
@@ -173,6 +180,8 @@ def GPR : RegisterClass<"ARM", [i32], 32, [R0, R1, R2, R3, R4, R5, R6,
       } else {
         if (Subtarget.isR9Reserved())
           return ARM_GPR_AO_2;
+        else if (Subtarget.isThumb())
+          return ARM_GPR_AO_5;
         else
           return ARM_GPR_AO_1;
       }
@@ -193,6 +202,8 @@ def GPR : RegisterClass<"ARM", [i32], 32, [R0, R1, R2, R3, R4, R5, R6,
       } else {
         if (Subtarget.isR9Reserved())
           I = ARM_GPR_AO_2 + (sizeof(ARM_GPR_AO_2)/sizeof(unsigned));
+        else if (Subtarget.isThumb())
+          I = ARM_GPR_AO_5 + (sizeof(ARM_GPR_AO_5)/sizeof(unsigned));
         else
           I = ARM_GPR_AO_1 + (sizeof(ARM_GPR_AO_1)/sizeof(unsigned));
       }
diff --git a/test/CodeGen/Thumb2/2009-08-04-CoalescerAssert.ll b/test/CodeGen/Thumb2/2009-08-04-CoalescerAssert.ll
new file mode 100644
index 00000000000..3486b7110f8
--- /dev/null
+++ b/test/CodeGen/Thumb2/2009-08-04-CoalescerAssert.ll
@@ -0,0 +1,29 @@
+; RUN: llvm-as < %s | llc -mtriple=thumbv7-none-linux-gnueabi
+; PR4681
+
+	%struct.FILE = type { i32, i8*, i8*, i8*, i8*, i8*, i8*, i8*, i8*, i8*, i8*, i8*, %struct._IO_marker*, %struct.FILE*, i32, i32, i32, i16, i8, [1 x i8], i8*, i64, i8*, i8*, i8*, i8*, i32, i32, [40 x i8] }
+	%struct._IO_marker = type { %struct._IO_marker*, %struct.FILE*, i32 }
+@.str2 = external constant [30 x i8], align 1		; <[30 x i8]*> [#uses=1]
+
+define arm_aapcscc i32 @__mf_heuristic_check(i32 %ptr, i32 %ptr_high) nounwind {
+entry:
+	br i1 undef, label %bb1, label %bb
+
+bb:		; preds = %entry
+	unreachable
+
+bb1:		; preds = %entry
+	br i1 undef, label %bb9, label %bb2
+
+bb2:		; preds = %bb1
+	%0 = call i8* @llvm.frameaddress(i32 0)		; <i8*> [#uses=1]
+	%1 = call arm_aapcscc  i32 (%struct.FILE*, i8*, ...)* @fprintf(%struct.FILE* noalias undef, i8* noalias getelementptr ([30 x i8]* @.str2, i32 0, i32 0), i8* %0, i8* null) nounwind		; <i32> [#uses=0]
+	unreachable
+
+bb9:		; preds = %bb1
+	ret i32 undef
+}
+
+declare i8* @llvm.frameaddress(i32) nounwind readnone
+
+declare arm_aapcscc i32 @fprintf(%struct.FILE* noalias nocapture, i8* noalias nocapture, ...) nounwind