diff --git a/lib/CodeGen/PHIElimination.cpp b/lib/CodeGen/PHIElimination.cpp
index 948511c5fb1..cd38dd144c5 100644
--- a/lib/CodeGen/PHIElimination.cpp
+++ b/lib/CodeGen/PHIElimination.cpp
@@ -449,14 +449,12 @@ MachineBasicBlock *PHIElimination::SplitCriticalEdge(MachineBasicBlock *A,
   MachineFunction *MF = A->getParent();
 
   // We may need to update A's terminator, but we can't do that if AnalyzeBranch
-  // fails.
-  if (A->isLayoutSuccessor(B)) {
-    const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
-    MachineBasicBlock *TBB = 0, *FBB = 0;
-    SmallVector<MachineOperand, 4> Cond;
-    if (!TII->AnalyzeBranch(*A, TBB, FBB, Cond))
-      return NULL;
-  }
+  // fails. If A uses a jump table, we won't touch it.
+  const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
+  MachineBasicBlock *TBB = 0, *FBB = 0;
+  SmallVector<MachineOperand, 4> Cond;
+  if (TII->AnalyzeBranch(*A, TBB, FBB, Cond))
+    return NULL;
 
   ++NumSplits;
 
@@ -474,7 +472,7 @@ MachineBasicBlock *PHIElimination::SplitCriticalEdge(MachineBasicBlock *A,
 
   // Insert unconditional "jump B" instruction in NMBB.
   NMBB->addSuccessor(B);
-  SmallVector<MachineOperand, 4> Cond;
+  Cond.clear();
   MF->getTarget().getInstrInfo()->InsertBranch(*NMBB, B, NULL, Cond);
 
   // Fix PHI nodes in B so they refer to NMBB instead of A
diff --git a/test/CodeGen/X86/2009-11-17-UpdateTerminator.ll b/test/CodeGen/X86/2009-11-17-UpdateTerminator.ll
new file mode 100644
index 00000000000..5c1a2bcee2e
--- /dev/null
+++ b/test/CodeGen/X86/2009-11-17-UpdateTerminator.ll
@@ -0,0 +1,52 @@
+; RUN: llc -O3 < %s
+; This test fails with:
+; Assertion failed: (!B && "UpdateTerminators requires analyzable predecessors!"), function updateTerminator, MachineBasicBlock.cpp, line 255.
+
+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"
+
+%"struct.llvm::InlineAsm::ConstraintInfo" = type { i32, i8, i8, i8, i8, %"struct.std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >,std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >" }
+%"struct.std::_Vector_base<llvm::InlineAsm::ConstraintInfo,std::allocator<llvm::InlineAsm::ConstraintInfo> >" = type { %"struct.std::_Vector_base<llvm::InlineAsm::ConstraintInfo,std::allocator<llvm::InlineAsm::ConstraintInfo> >::_Vector_impl" }
+%"struct.std::_Vector_base<llvm::InlineAsm::ConstraintInfo,std::allocator<llvm::InlineAsm::ConstraintInfo> >::_Vector_impl" = type { %"struct.llvm::InlineAsm::ConstraintInfo"*, %"struct.llvm::InlineAsm::ConstraintInfo"*, %"struct.llvm::InlineAsm::ConstraintInfo"* }
+%"struct.std::_Vector_base<std::basic_string<char, std::char_traits<char>, std::allocator<char> >,std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >" = type { %"struct.std::_Vector_base<std::basic_string<char, std::char_traits<char>, std::allocator<char> >,std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >::_Vector_impl" }
+%"struct.std::_Vector_base<std::basic_string<char, std::char_traits<char>, std::allocator<char> >,std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >::_Vector_impl" = type { %"struct.std::string"*, %"struct.std::string"*, %"struct.std::string"* }
+%"struct.std::basic_string<char,std::char_traits<char>,std::allocator<char> >::_Alloc_hider" = type { i8* }
+%"struct.std::string" = type { %"struct.std::basic_string<char,std::char_traits<char>,std::allocator<char> >::_Alloc_hider" }
+%"struct.std::vector<llvm::InlineAsm::ConstraintInfo,std::allocator<llvm::InlineAsm::ConstraintInfo> >" = type { %"struct.std::_Vector_base<llvm::InlineAsm::ConstraintInfo,std::allocator<llvm::InlineAsm::ConstraintInfo> >" }
+%"struct.std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >,std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >" = type { %"struct.std::_Vector_base<std::basic_string<char, std::char_traits<char>, std::allocator<char> >,std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >" }
+
+define zeroext i8 @_ZN4llvm9InlineAsm14ConstraintInfo5ParseENS_9StringRefERSt6vectorIS1_SaIS1_EE(%"struct.llvm::InlineAsm::ConstraintInfo"* nocapture %this, i64 %Str.0, i64 %Str.1, %"struct.std::vector<llvm::InlineAsm::ConstraintInfo,std::allocator<llvm::InlineAsm::ConstraintInfo> >"* nocapture %ConstraintsSoFar) nounwind ssp align 2 {
+entry:
+  br i1 undef, label %bb56, label %bb27.outer
+
+bb8:                                              ; preds = %bb27.outer108, %bb13
+  switch i8 undef, label %bb27.outer [
+    i8 35, label %bb56
+    i8 37, label %bb14
+    i8 38, label %bb10
+    i8 42, label %bb56
+  ]
+
+bb27.outer:                                       ; preds = %bb8, %entry
+  %I.2.ph = phi i8* [ undef, %entry ], [ %I.2.ph109, %bb8 ] ; <i8*> [#uses=2]
+  br label %bb27.outer108
+
+bb10:                                             ; preds = %bb8
+  %toBool = icmp eq i8 0, 0                       ; <i1> [#uses=1]
+  %or.cond = and i1 undef, %toBool                ; <i1> [#uses=1]
+  br i1 %or.cond, label %bb13, label %bb56
+
+bb13:                                             ; preds = %bb10
+  br i1 undef, label %bb27.outer108, label %bb8
+
+bb14:                                             ; preds = %bb8
+  ret i8 1
+
+bb27.outer108:                                    ; preds = %bb13, %bb27.outer
+  %I.2.ph109 = getelementptr i8* %I.2.ph, i64 undef ; <i8*> [#uses=1]
+  %scevgep = getelementptr i8* %I.2.ph, i64 undef ; <i8*> [#uses=0]
+  br label %bb8
+
+bb56:                                             ; preds = %bb10, %bb8, %bb8, %entry
+  ret i8 1
+}