diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp
index 1ff3af92fad..a2d521b139a 100644
--- a/lib/CodeGen/SimpleRegisterCoalescing.cpp
+++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp
@@ -123,7 +123,8 @@ bool SimpleRegisterCoalescing::AdjustCopiesBackFrom(LiveInterval &IntA,
   assert(BValNo->def == CopyIdx && "Copy doesn't define the value?");
   
   // AValNo is the value number in A that defines the copy, A3 in the example.
-  LiveInterval::iterator ALR = IntA.FindLiveRangeContaining(CopyIdx-1);
+  unsigned CopyUseIdx = li_->getUseIndex(CopyIdx);
+  LiveInterval::iterator ALR = IntA.FindLiveRangeContaining(CopyUseIdx);
   assert(ALR != IntA.end() && "Live range not found!");
   VNInfo *AValNo = ALR->valno;
   // If it's re-defined by an early clobber somewhere in the live range, then
@@ -227,6 +228,12 @@ bool SimpleRegisterCoalescing::AdjustCopiesBackFrom(LiveInterval &IntA,
     IntB.removeKill(ValLR->valno, FillerStart);
   }
 
+  // If the copy instruction was killing the destination register before the
+  // merge, find the last use and trim the live range. That will also add the
+  // isKill marker.
+  if (CopyMI->killsRegister(IntA.reg))
+    TrimLiveIntervalToLastUse(CopyUseIdx, CopyMI->getParent(), IntA, ALR);
+
   ++numExtends;
   return true;
 }
diff --git a/test/CodeGen/Thumb2/2009-08-02-CoalescerBug.ll b/test/CodeGen/Thumb2/2009-08-02-CoalescerBug.ll
new file mode 100644
index 00000000000..2f4683a43f7
--- /dev/null
+++ b/test/CodeGen/Thumb2/2009-08-02-CoalescerBug.ll
@@ -0,0 +1,46 @@
+; RUN: llvm-as < %s | llc -mtriple=thumbv7-apple-darwin9 -mcpu=cortex-a8 -relocation-model=pic -disable-fp-elim
+
+	type { void (%"struct.xalanc_1_8::FormatterToXML"*, i16)*, i32 }		; type %0
+	type { void (%"struct.xalanc_1_8::FormatterToXML"*, i16*)*, i32 }		; type %1
+	type { void (%"struct.xalanc_1_8::FormatterToXML"*, %"struct.xalanc_1_8::XalanDOMString"*)*, i32 }		; type %2
+	type { void (%"struct.xalanc_1_8::FormatterToXML"*, i16*, i32, i32)*, i32 }		; type %3
+	type { void (%"struct.xalanc_1_8::FormatterToXML"*)*, i32 }		; type %4
+	%"struct.std::CharVectorType" = type { %"struct.std::_Vector_base<char,std::allocator<char> >" }
+	%"struct.std::_Bit_const_iterator" = type { %"struct.std::_Bit_iterator_base" }
+	%"struct.std::_Bit_iterator_base" = type { i32*, i32 }
+	%"struct.std::_Bvector_base<std::allocator<bool> >" = type { %"struct.std::_Bvector_base<std::allocator<bool> >::_Bvector_impl" }
+	%"struct.std::_Bvector_base<std::allocator<bool> >::_Bvector_impl" = type { %"struct.std::_Bit_const_iterator", %"struct.std::_Bit_const_iterator", i32* }
+	%"struct.std::_Vector_base<char,std::allocator<char> >" = type { %"struct.std::_Vector_base<char,std::allocator<char> >::_Vector_impl" }
+	%"struct.std::_Vector_base<char,std::allocator<char> >::_Vector_impl" = type { i8*, i8*, i8* }
+	%"struct.std::_Vector_base<short unsigned int,std::allocator<short unsigned int> >" = type { %"struct.std::_Vector_base<short unsigned int,std::allocator<short unsigned int> >::_Vector_impl" }
+	%"struct.std::_Vector_base<short unsigned int,std::allocator<short unsigned int> >::_Vector_impl" = type { i16*, i16*, i16* }
+	%"struct.std::basic_ostream<char,std::char_traits<char> >.base" = type { i32 (...)** }
+	%"struct.std::vector<bool,std::allocator<bool> >" = type { %"struct.std::_Bvector_base<std::allocator<bool> >" }
+	%"struct.std::vector<short unsigned int,std::allocator<short unsigned int> >" = type { %"struct.std::_Vector_base<short unsigned int,std::allocator<short unsigned int> >" }
+	%"struct.xalanc_1_8::FormatterListener" = type { %"struct.std::basic_ostream<char,std::char_traits<char> >.base", %"struct.std::basic_ostream<char,std::char_traits<char> >.base"*, i32 }
+	%"struct.xalanc_1_8::FormatterToXML" = type { %"struct.xalanc_1_8::FormatterListener", %"struct.std::basic_ostream<char,std::char_traits<char> >.base"*, %"struct.xalanc_1_8::XalanOutputStream"*, i16, [256 x i16], [256 x i16], i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, %"struct.xalanc_1_8::XalanDOMString", %"struct.xalanc_1_8::XalanDOMString", %"struct.xalanc_1_8::XalanDOMString", i32, i32, %"struct.std::vector<bool,std::allocator<bool> >", %"struct.xalanc_1_8::XalanDOMString", i8, i8, i8, i8, i8, %"struct.xalanc_1_8::XalanDOMString", %"struct.xalanc_1_8::XalanDOMString", %"struct.xalanc_1_8::XalanDOMString", %"struct.xalanc_1_8::XalanDOMString", %"struct.std::vector<short unsigned int,std::allocator<short unsigned int> >", i32, %"struct.std::CharVectorType", %"struct.std::vector<bool,std::allocator<bool> >", %0, %1, %2, %3, %0, %1, %2, %3, %4, i16*, i32 }
+	%"struct.xalanc_1_8::XalanDOMString" = type { %"struct.std::vector<short unsigned int,std::allocator<short unsigned int> >", i32 }
+	%"struct.xalanc_1_8::XalanOutputStream" = type { i32 (...)**, i32, %"struct.std::basic_ostream<char,std::char_traits<char> >.base"*, i32, %"struct.std::vector<short unsigned int,std::allocator<short unsigned int> >", %"struct.xalanc_1_8::XalanDOMString", i8, i8, %"struct.std::CharVectorType" }
+
+declare arm_apcscc void @_ZN10xalanc_1_814FormatterToXML17writeParentTagEndEv(%"struct.xalanc_1_8::FormatterToXML"*)
+
+define arm_apcscc void @_ZN10xalanc_1_814FormatterToXML5cdataEPKtj(%"struct.xalanc_1_8::FormatterToXML"* %this, i16* %ch, i32 %length) {
+entry:
+	%0 = getelementptr %"struct.xalanc_1_8::FormatterToXML"* %this, i32 0, i32 13		; <i8*> [#uses=1]
+	br i1 undef, label %bb4, label %bb
+
+bb:		; preds = %entry
+	store i8 0, i8* %0, align 1
+	%1 = getelementptr %"struct.xalanc_1_8::FormatterToXML"* %this, i32 0, i32 0, i32 0, i32 0		; <i32 (...)***> [#uses=1]
+	%2 = load i32 (...)*** %1, align 4		; <i32 (...)**> [#uses=1]
+	%3 = getelementptr i32 (...)** %2, i32 11		; <i32 (...)**> [#uses=1]
+	%4 = load i32 (...)** %3, align 4		; <i32 (...)*> [#uses=1]
+	%5 = bitcast i32 (...)* %4 to void (%"struct.xalanc_1_8::FormatterToXML"*, i16*, i32)*		; <void (%"struct.xalanc_1_8::FormatterToXML"*, i16*, i32)*> [#uses=1]
+	tail call arm_apcscc  void %5(%"struct.xalanc_1_8::FormatterToXML"* %this, i16* %ch, i32 %length)
+	ret void
+
+bb4:		; preds = %entry
+	tail call arm_apcscc  void @_ZN10xalanc_1_814FormatterToXML17writeParentTagEndEv(%"struct.xalanc_1_8::FormatterToXML"* %this)
+	tail call arm_apcscc  void undef(%"struct.xalanc_1_8::FormatterToXML"* %this, i16* %ch, i32 0, i32 %length, i8 zeroext undef)
+	ret void
+}