diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -1297,7 +1297,6 @@
       continue;
     }
 
-    if (isa<PHINode>(InVal)) return nullptr;  // Itself a phi.
     if (NonSimplifiedBB) return nullptr;  // More than one non-simplified value.
 
     NonSimplifiedBB = InBB;
diff --git a/llvm/test/Analysis/ValueTracking/known-power-of-two-urem.ll b/llvm/test/Analysis/ValueTracking/known-power-of-two-urem.ll
--- a/llvm/test/Analysis/ValueTracking/known-power-of-two-urem.ll
+++ b/llvm/test/Analysis/ValueTracking/known-power-of-two-urem.ll
@@ -15,12 +15,11 @@
 ; CHECK:       cond.true.false:
 ; CHECK-NEXT:    br label [[COND_TRUE_END]]
 ; CHECK:       cond.true.end:
-; CHECK-NEXT:    [[PHI:%.*]] = phi i64 [ 2, [[COND_TRUE_TRUE]] ], [ 4, [[COND_TRUE_FALSE]] ]
+; CHECK-NEXT:    [[PHI:%.*]] = phi i64 [ 1, [[COND_TRUE_TRUE]] ], [ 3, [[COND_TRUE_FALSE]] ]
 ; CHECK-NEXT:    br label [[COND_END]]
 ; CHECK:       cond.end:
-; CHECK-NEXT:    [[PHI1:%.*]] = phi i64 [ 4096, [[ENTRY:%.*]] ], [ [[PHI]], [[COND_TRUE_END]] ]
-; CHECK-NEXT:    [[TMP0:%.*]] = add nsw i64 [[PHI1]], -1
-; CHECK-NEXT:    [[UREM:%.*]] = and i64 [[TMP0]], [[SIZE:%.*]]
+; CHECK-NEXT:    [[PHI1:%.*]] = phi i64 [ 4095, [[ENTRY:%.*]] ], [ [[PHI]], [[COND_TRUE_END]] ]
+; CHECK-NEXT:    [[UREM:%.*]] = and i64 [[PHI1]], [[SIZE:%.*]]
 ; CHECK-NEXT:    ret i64 [[UREM]]
 ;
 entry: