Index: lib/Transforms/Scalar/GuardWidening.cpp
===================================================================
--- lib/Transforms/Scalar/GuardWidening.cpp
+++ lib/Transforms/Scalar/GuardWidening.cpp
@@ -344,6 +344,15 @@
     Instruction *GuardInst, const df_iterator<DomTreeNode *> &DFSI,
     const DenseMap<BasicBlock *, SmallVector<Instruction *, 8>> &
         GuardsInBlock, bool InvertCondition) {
+  auto *Cond = getCondition(GuardInst);
+  auto *True = ConstantInt::getTrue(GuardInst->getContext());
+  auto *False = ConstantInt::getFalse(GuardInst->getContext());
+  // Ignore trivial true or false conditions. These instructions will be
+  // trivially eliminated by any cleanup pass. Do not erase them because other
+  // guards can possibly be widened into them.
+  if (Cond == True || Cond == False)
+    return false;
+
   Instruction *BestSoFar = nullptr;
   auto BestScoreSoFar = WS_IllegalOrNegative;
   auto *GuardInstLoop = LI.getLoopFor(GuardInst->getParent());
@@ -388,7 +397,7 @@
     for (auto *Candidate : make_range(I, E)) {
       auto Score =
           computeWideningScore(GuardInst, GuardInstLoop, Candidate, CurLoop);
-      LLVM_DEBUG(dbgs() << "Score between " << *getCondition(GuardInst)
+      LLVM_DEBUG(dbgs() << "Score between " << *Cond
                         << " and " << *getCondition(Candidate) << " is "
                         << scoreTypeToString(Score) << "\n");
       if (Score > BestScoreSoFar) {
@@ -410,9 +419,7 @@
                     << " with score " << scoreTypeToString(BestScoreSoFar)
                     << "\n");
   widenGuard(BestSoFar, getCondition(GuardInst), InvertCondition);
-  auto NewGuardCondition = InvertCondition
-                               ? ConstantInt::getFalse(GuardInst->getContext())
-                               : ConstantInt::getTrue(GuardInst->getContext());
+  auto *NewGuardCondition = InvertCondition ? False : True;
   setCondition(GuardInst, NewGuardCondition);
   EliminatedGuardsAndBranches.push_back(GuardInst);
   WidenedGuards.insert(BestSoFar);
Index: test/Transforms/GuardWidening/basic.ll
===================================================================
--- test/Transforms/GuardWidening/basic.ll
+++ test/Transforms/GuardWidening/basic.ll
@@ -379,3 +379,29 @@
 right:
   ret void
 }
+
+; Make sure we do not widen guard by trivial true conditions into something.
+define void @f_15(i1 %cond_0, i1 %cond_1) {
+; CHECK-LABEL: @f_15(
+entry:
+; CHECK:  call void (i1, ...) @llvm.experimental.guard(i1 %cond_0) [ "deopt"() ]
+; CHECK:  call void (i1, ...) @llvm.experimental.guard(i1 true) [ "deopt"() ]
+; CHECK:  ret void
+
+  call void(i1, ...) @llvm.experimental.guard(i1 %cond_0) [ "deopt"() ]
+  call void(i1, ...) @llvm.experimental.guard(i1 true) [ "deopt"() ]
+  ret void
+}
+
+; Make sure we do not widen guard by trivial false conditions into something.
+define void @f_16(i1 %cond_0, i1 %cond_1) {
+; CHECK-LABEL: @f_16(
+entry:
+; CHECK:  call void (i1, ...) @llvm.experimental.guard(i1 %cond_0) [ "deopt"() ]
+; CHECK:  call void (i1, ...) @llvm.experimental.guard(i1 false) [ "deopt"() ]
+; CHECK:  ret void
+
+  call void(i1, ...) @llvm.experimental.guard(i1 %cond_0) [ "deopt"() ]
+  call void(i1, ...) @llvm.experimental.guard(i1 false) [ "deopt"() ]
+  ret void
+}