diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
index c2caf48b7616..b17f80d39c0f 100644
--- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
@@ -341,25 +341,21 @@ ComputeValueKnownInPredecessors(Value *V, BasicBlock *BB,PredValueInfo &Result){
       else
         InterestingVal = ConstantInt::getFalse(I->getContext());
       
+      SmallPtrSet<BasicBlock*, 4> LHSKnownBBs;
+      
       // Scan for the sentinel.  If we find an undef, force it to the
       // interesting value: x|undef -> true and x&undef -> false.
       for (unsigned i = 0, e = LHSVals.size(); i != e; ++i)
         if (LHSVals[i].first == InterestingVal || LHSVals[i].first == 0) {
           Result.push_back(LHSVals[i]);
           Result.back().first = InterestingVal;
+          LHSKnownBBs.insert(LHSVals[i].second);
         }
       for (unsigned i = 0, e = RHSVals.size(); i != e; ++i)
         if (RHSVals[i].first == InterestingVal || RHSVals[i].first == 0) {
           // If we already inferred a value for this block on the LHS, don't
           // re-add it.
-          bool HasValue = false;
-          for (unsigned r = 0, e = Result.size(); r != e; ++r)
-            if (Result[r].second == RHSVals[i].second) {
-              HasValue = true;
-              break;
-            }
-          
-          if (!HasValue) {
+          if (!LHSKnownBBs.count(RHSVals[i].second)) {
             Result.push_back(RHSVals[i]);
             Result.back().first = InterestingVal;
           }
diff --git a/llvm/test/Transforms/JumpThreading/crash.ll b/llvm/test/Transforms/JumpThreading/crash.ll
index 4fe94e5ea0c6..cfd904243125 100644
--- a/llvm/test/Transforms/JumpThreading/crash.ll
+++ b/llvm/test/Transforms/JumpThreading/crash.ll
@@ -436,4 +436,28 @@ for.cond1040:                                     ; preds = %for.body1044, %for.
   ret void
 }
 
+; PR7755
+define void @test16(i1 %c, i1 %c2, i1 %c3, i1 %c4) nounwind ssp {
+entry:
+  %cmp = icmp sgt i32 undef, 1                    ; <i1> [#uses=1]
+  br i1 %c, label %land.end, label %land.rhs
+
+land.rhs:                                         ; preds = %entry
+  br i1 %c2, label %lor.lhs.false.i, label %land.end
+
+lor.lhs.false.i:                                  ; preds = %land.rhs
+  br i1 %c3, label %land.end, label %land.end
+
+land.end:                            
+  %0 = phi i1 [ true, %entry ], [ false, %land.rhs ], [false, %lor.lhs.false.i], [false, %lor.lhs.false.i] ; <i1> [#uses=1]
+  %cmp12 = and i1 %cmp, %0 
+  %xor1 = xor i1 %cmp12, %c4
+  br i1 %xor1, label %if.then, label %if.end
+
+if.then:                      
+  ret void
+
+if.end:                       
+  ret void
+}