diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index 4b9b648aa6c..156e7853059 100644
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -395,17 +395,39 @@ static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS,
   assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
   SelectInst *SI = cast<SelectInst>(LHS);
 
-  // Now that we have "cmp select(cond, TV, FV), RHS", analyse it.
+  // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it.
   // Does "cmp TV, RHS" simplify?
   if (Value *TCmp = SimplifyCmpInst(Pred, SI->getTrueValue(), RHS, TD, DT,
-                                    MaxRecurse))
+                                    MaxRecurse)) {
     // It does!  Does "cmp FV, RHS" simplify?
     if (Value *FCmp = SimplifyCmpInst(Pred, SI->getFalseValue(), RHS, TD, DT,
-                                      MaxRecurse))
+                                      MaxRecurse)) {
       // It does!  If they simplified to the same value, then use it as the
       // result of the original comparison.
       if (TCmp == FCmp)
         return TCmp;
+      Value *Cond = SI->getCondition();
+      // If the false value simplified to false, then the result of the compare
+      // is equal to "Cond && TCmp".  This also catches the case when the false
+      // value simplified to false and the true value to true, returning "Cond".
+      if (match(FCmp, m_Zero()))
+        if (Value *V = SimplifyAndInst(Cond, TCmp, TD, DT, MaxRecurse))
+          return V;
+      // If the true value simplified to true, then the result of the compare
+      // is equal to "Cond || FCmp".
+      if (match(TCmp, m_One()))
+        if (Value *V = SimplifyOrInst(Cond, FCmp, TD, DT, MaxRecurse))
+          return V;
+      // Finally, if the false value simplified to true and the true value to
+      // false, then the result of the compare is equal to "!Cond".
+      if (match(FCmp, m_One()) && match(TCmp, m_Zero()))
+        if (Value *V =
+            SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()),
+                            TD, DT, MaxRecurse))
+          return V;
+    }
+  }
+
   return 0;
 }
 
diff --git a/test/Transforms/InstSimplify/2011-01-18-Compare.ll b/test/Transforms/InstSimplify/2011-01-18-Compare.ll
index ed358443d63..e08ee2c6fb5 100644
--- a/test/Transforms/InstSimplify/2011-01-18-Compare.ll
+++ b/test/Transforms/InstSimplify/2011-01-18-Compare.ll
@@ -132,3 +132,38 @@ define i1 @ashr(i32 %x) {
   ret i1 %c
 ; CHECK: ret i1 false
 }
+
+define i1 @select1(i1 %cond) {
+; CHECK: @select1
+  %s = select i1 %cond, i32 1, i32 0
+  %c = icmp eq i32 %s, 1
+  ret i1 %c
+; CHECK: ret i1 %cond
+}
+
+define i1 @select2(i1 %cond) {
+; CHECK: @select2
+  %x = zext i1 %cond to i32
+  %s = select i1 %cond, i32 %x, i32 0
+  %c = icmp ne i32 %s, 0
+  ret i1 %c
+; CHECK: ret i1 %cond
+}
+
+define i1 @select3(i1 %cond) {
+; CHECK: @select3
+  %x = zext i1 %cond to i32
+  %s = select i1 %cond, i32 1, i32 %x
+  %c = icmp ne i32 %s, 0
+  ret i1 %c
+; CHECK: ret i1 %cond
+}
+
+define i1 @select4(i1 %cond) {
+; CHECK: @select4
+  %invert = xor i1 %cond, 1
+  %s = select i1 %invert, i32 0, i32 1
+  %c = icmp ne i32 %s, 0
+  ret i1 %c
+; CHECK: ret i1 %cond
+}