diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index f426fb1f3fa..05f9f1ff186 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -1038,6 +1038,8 @@ SelectionDAGISel::FinishBasicBlock() {
       MachineInstr *PHI = SDB->PHINodesToUpdate[i].first;
       assert(PHI->isPHI() &&
              "This is not a machine PHI node that we are updating!");
+      if (!BB->isSuccessor(PHI->getParent()))
+        continue;
       PHI->addOperand(MachineOperand::CreateReg(SDB->PHINodesToUpdate[i].second,
                                                 false));
       PHI->addOperand(MachineOperand::CreateMBB(BB));
diff --git a/test/CodeGen/X86/2010-03-05-ConstantFoldCFG.ll b/test/CodeGen/X86/2010-03-05-ConstantFoldCFG.ll
new file mode 100644
index 00000000000..5de19662fff
--- /dev/null
+++ b/test/CodeGen/X86/2010-03-05-ConstantFoldCFG.ll
@@ -0,0 +1,42 @@
+; RUN: llc < %s -verify-machineinstrs
+;
+; When BRCOND is constant-folded to BR, make sure that PHI nodes don't get
+; spurious operands when the CFG is trimmed.
+;
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+target triple = "x86_64-apple-darwin10.2"
+
+define fastcc void @_ZSt16__introsort_loopIPdl17less_than_functorEvT_S2_T0_T1_(double* %__first, double* %__last, i64 %__depth_limit) nounwind ssp {
+entry:
+  br i1 undef, label %bb1, label %bb2
+
+bb1:                                              ; preds = %entry
+  ret void
+
+bb2:                                              ; preds = %entry
+  br label %bb2.outer.i
+
+bb2.outer.i:                                      ; preds = %bb9.i, %bb2
+  br i1 undef, label %bb1.i, label %bb5.preheader.i
+
+bb1.i:                                            ; preds = %bb1.i, %bb2.outer.i
+  %indvar5.i = phi i64 [ %tmp, %bb1.i ], [ 0, %bb2.outer.i ] ; <i64> [#uses=1]
+  %tmp = add i64 %indvar5.i, 1                    ; <i64> [#uses=2]
+  %scevgep.i = getelementptr double* undef, i64 %tmp ; <double*> [#uses=0]
+  br i1 undef, label %bb1.i, label %bb5.preheader.i
+
+bb5.preheader.i:                                  ; preds = %bb1.i, %bb2.outer.i
+  br label %bb5.i
+
+bb5.i:                                            ; preds = %bb5.i, %bb5.preheader.i
+  br i1 undef, label %bb5.i, label %bb7.i6
+
+bb7.i6:                                           ; preds = %bb5.i
+  br i1 undef, label %bb9.i, label %_ZSt21__unguarded_partitionIPdd17less_than_functorET_S2_S2_T0_T1_.exit
+
+bb9.i:                                            ; preds = %bb7.i6
+  br label %bb2.outer.i
+
+_ZSt21__unguarded_partitionIPdd17less_than_functorET_S2_S2_T0_T1_.exit: ; preds = %bb7.i6
+  unreachable
+}