diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -2868,6 +2868,11 @@
     if (isImpliedCondition(LHS, RHS, Q.DL).value_or(false))
       return getTrue(ITy);
     break;
+  case ICmpInst::ICMP_SLE:
+    /// SLE follows the same logic as SGE with the LHS and RHS swapped.
+    if (isImpliedCondition(RHS, LHS, Q.DL).value_or(false))
+      return getTrue(ITy);
+    break;
   }
 
   return nullptr;
diff --git a/llvm/test/Transforms/InstSimplify/implies.ll b/llvm/test/Transforms/InstSimplify/implies.ll
--- a/llvm/test/Transforms/InstSimplify/implies.ll
+++ b/llvm/test/Transforms/InstSimplify/implies.ll
@@ -255,3 +255,15 @@
   %res = icmp sge i1 %var30, %var29
   ret i1 %res
 }
+
+; X <=(s) Y == Y ==> X (i1 1 becomes -1 for reasoning)
+define i1 @test_sle(i32 %length.i, i32 %i) {
+; CHECK-LABEL: @test_sle(
+; CHECK-NEXT:    ret i1 true
+;
+  %iplus1 = add nsw nuw i32 %i, 1
+  %var29 = icmp ult i32 %i, %length.i
+  %var30 = icmp ult i32 %iplus1, %length.i
+  %res = icmp sle i1 %var29, %var30
+  ret i1 %res
+}