diff --git a/lib/Analysis/LazyValueInfo.cpp b/lib/Analysis/LazyValueInfo.cpp
index 9f919f7644a..281ff89bfe4 100644
--- a/lib/Analysis/LazyValueInfo.cpp
+++ b/lib/Analysis/LazyValueInfo.cpp
@@ -500,8 +500,23 @@ bool LazyValueInfoCache::solveBlockValue(Value *Val, BasicBlock *BB) {
   // cache needs updating, i.e. if we have solve a new value or not.
   OverDefinedCacheUpdater ODCacheUpdater(Val, BB, BBLV, this);
 
-  // If we've already computed this block's value, return it.
-  if (!BBLV.isUndefined()) {
+  // Once this BB is encountered, Val's value for this BB will not be Undefined
+  // any longer. When we encounter this BB again, if Val's value is Overdefined,
+  // we need to compute its value again.
+  // 
+  // For example, considering this control flow,
+  //   BB1->BB2, BB1->BB3, BB2->BB3, BB2->BB4
+  //
+  // Suppose we have "icmp slt %v, 0" in BB1, and "icmp sgt %v, 0" in BB3. At
+  // the very beginning, when analyzing edge BB2->BB3, we don't know %v's value
+  // in BB2, and the data flow algorithm tries to compute BB2's predecessors, so
+  // then we know %v has negative value on edge BB1->BB2. And then we return to
+  // check BB2 again, and at this moment BB2 has Overdefined value for %v in
+  // BB2. So we should have to follow data flow propagation algorithm to get the
+  // value on edge BB1->BB2 propagated to BB2, and finally %v on BB2 has a
+  // constant range describing a negative value.
+
+  if (!BBLV.isUndefined() && !BBLV.isOverdefined()) {
     DEBUG(dbgs() << "  reuse BB '" << BB->getName() << "' val=" << BBLV <<'\n');
     
     // Since we're reusing a cached value here, we don't need to update the 
diff --git a/test/Transforms/JumpThreading/jump_threading.ll b/test/Transforms/JumpThreading/jump_threading.ll
new file mode 100644
index 00000000000..f5a0ead3d90
--- /dev/null
+++ b/test/Transforms/JumpThreading/jump_threading.ll
@@ -0,0 +1,33 @@
+; RUN: opt < %s -jump-threading -S | FileCheck %s
+
+define i32 @test_jump_threading(i32* %arg1, i32 %arg2) {
+entry:
+  %cmp = icmp slt i32 %arg2, 0
+  br i1 %cmp, label %land.lhs.true, label %lor.rhs
+
+land.lhs.true:
+  %ident = getelementptr inbounds i32 * %arg1, i64 0
+  %0 = load i32* %ident, align 4
+  %cmp1 = icmp eq i32 %0, 1
+  br i1 %cmp1, label %lor.end, label %lor.rhs
+
+; CHECK: br i1 %cmp1, label %lor.end, label %lor.rhs.thread
+
+; CHECK: lor.rhs.thread:
+; CHECK-NEXT: br label %lor.end
+
+lor.rhs:
+  %cmp2 = icmp sgt i32 %arg2, 0
+  br i1 %cmp2, label %land.rhs, label %lor.end
+
+land.rhs:
+  %ident3 = getelementptr inbounds i32 * %arg1, i64 0
+  %1 = load i32* %ident3, align 4
+  %cmp4 = icmp eq i32 %1, 2
+  br label %lor.end
+
+lor.end:
+  %2 = phi i1 [ true, %land.lhs.true ], [ false, %lor.rhs ], [ %cmp4, %land.rhs ]
+  %lor.ext = zext i1 %2 to i32
+  ret i32 %lor.ext
+}