Index: llvm/trunk/lib/Transforms/Scalar/LoopPredication.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopPredication.cpp
+++ llvm/trunk/lib/Transforms/Scalar/LoopPredication.cpp
@@ -155,7 +155,7 @@
 // When S = -1 (i.e. reverse iterating loop), the transformation is supported
 // when:
 //   * The loop has a single latch with the condition of the form:
-//     B(X) = X <pred> latchLimit, where <pred> is u> or s>.
+//     B(X) = X <pred> latchLimit, where <pred> is u>, u>=, s>, or s>=.
 //   * The guard condition is of the form
 //     G(X) = X - 1 u< guardLimit
 //
@@ -171,6 +171,10 @@
 //     guardStart u< guardLimit && latchLimit u>= 1.
 //   Similarly for sgt condition the widened condition is:
 //     guardStart u< guardLimit && latchLimit s>= 1.
+//   For uge condition the widened condition is:
+//     guardStart u< guardLimit && latchLimit u> 1.
+//   For sge condition the widened condition is:
+//     guardStart u< guardLimit && latchLimit s> 1.
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Transforms/Scalar/LoopPredication.h"
@@ -485,9 +489,7 @@
   // latchLimit <pred> 1.
   // See the header comment for reasoning of the checks.
   Instruction *InsertAt = Preheader->getTerminator();
-  auto LimitCheckPred = ICmpInst::isSigned(LatchCheck.Pred)
-                            ? ICmpInst::ICMP_SGE
-                            : ICmpInst::ICMP_UGE;
+  auto LimitCheckPred = getLatchPredicateForGuard(LatchCheck.Pred);
   auto *FirstIterationCheck = expandCheck(Expander, Builder, ICmpInst::ICMP_ULT,
                                           GuardStart, GuardLimit, InsertAt);
   auto *LimitCheck = expandCheck(Expander, Builder, LimitCheckPred, LatchLimit,
@@ -671,7 +673,8 @@
              Pred != ICmpInst::ICMP_ULE && Pred != ICmpInst::ICMP_SLE;
     } else {
       assert(Step->isAllOnesValue() && "Step should be -1!");
-      return Pred != ICmpInst::ICMP_UGT && Pred != ICmpInst::ICMP_SGT;
+      return Pred != ICmpInst::ICMP_UGT && Pred != ICmpInst::ICMP_SGT &&
+             Pred != ICmpInst::ICMP_UGE && Pred != ICmpInst::ICMP_SGE;
     }
   };
 
Index: llvm/trunk/test/Transforms/LoopPredication/reverse.ll
===================================================================
--- llvm/trunk/test/Transforms/LoopPredication/reverse.ll
+++ llvm/trunk/test/Transforms/LoopPredication/reverse.ll
@@ -138,3 +138,108 @@
   %result = phi i32 [ 0, %entry ], [ %loop.acc.next, %loop ]
   ret i32 %result
 }
+
+define i32 @signed_reverse_loop_n_to_lower_limit_equal(i32* %array, i32 %length, i32 %n, i32 %lowerlimit) {
+; CHECK-LABEL: @signed_reverse_loop_n_to_lower_limit_equal(
+entry:
+  %tmp5 = icmp eq i32 %n, 0
+  br i1 %tmp5, label %exit, label %loop.preheader
+
+; CHECK:       loop.preheader:
+; CHECK-NEXT:    [[range_start:%.*]] = add i32 %n, -1
+; CHECK-NEXT:    [[first_iteration_check:%.*]] = icmp ult i32 [[range_start]], %length
+; CHECK-NEXT:    [[no_wrap_check:%.*]] = icmp sgt i32 %lowerlimit, 1
+; CHECK-NEXT:    [[wide_cond:%.*]] = and i1 [[first_iteration_check]], [[no_wrap_check]]
+loop.preheader:
+  br label %loop
+
+; CHECK: loop:
+; CHECK:    call void (i1, ...) @llvm.experimental.guard(i1 [[wide_cond]], i32 9) [ "deopt"() ]
+loop:
+  %loop.acc = phi i32 [ %loop.acc.next, %loop ], [ 0, %loop.preheader ]
+  %i = phi i32 [ %i.next, %loop ], [ %n, %loop.preheader ]
+  %i.next = add nsw i32 %i, -1
+  %within.bounds = icmp ult i32 %i.next, %length
+  call void (i1, ...) @llvm.experimental.guard(i1 %within.bounds, i32 9) [ "deopt"() ]
+  %i.i64 = zext i32 %i.next to i64
+  %array.i.ptr = getelementptr inbounds i32, i32* %array, i64 %i.i64
+  %array.i = load i32, i32* %array.i.ptr, align 4
+  %loop.acc.next = add i32 %loop.acc, %array.i
+  %continue = icmp sge i32 %i, %lowerlimit
+  br i1 %continue, label %loop, label %exit
+
+exit:
+  %result = phi i32 [ 0, %entry ], [ %loop.acc.next, %loop ]
+  ret i32 %result
+}
+
+define i32 @unsigned_reverse_loop_n_to_lower_limit_equal(i32* %array, i32 %length, i32 %n, i32 %lowerlimit) {
+; CHECK-LABEL: @unsigned_reverse_loop_n_to_lower_limit_equal(
+entry:
+  %tmp5 = icmp eq i32 %n, 0
+  br i1 %tmp5, label %exit, label %loop.preheader
+
+; CHECK:       loop.preheader:
+; CHECK-NEXT:    [[range_start:%.*]] = add i32 %n, -1
+; CHECK-NEXT:    [[first_iteration_check:%.*]] = icmp ult i32 [[range_start]], %length
+; CHECK-NEXT:    [[no_wrap_check:%.*]] = icmp ugt i32 %lowerlimit, 1
+; CHECK-NEXT:    [[wide_cond:%.*]] = and i1 [[first_iteration_check]], [[no_wrap_check]]
+loop.preheader:
+  br label %loop
+
+; CHECK: loop:
+; CHECK:    call void (i1, ...) @llvm.experimental.guard(i1 [[wide_cond]], i32 9) [ "deopt"() ]
+loop:
+  %loop.acc = phi i32 [ %loop.acc.next, %loop ], [ 0, %loop.preheader ]
+  %i = phi i32 [ %i.next, %loop ], [ %n, %loop.preheader ]
+  %i.next = add nsw i32 %i, -1
+  %within.bounds = icmp ult i32 %i.next, %length
+  call void (i1, ...) @llvm.experimental.guard(i1 %within.bounds, i32 9) [ "deopt"() ]
+  %i.i64 = zext i32 %i.next to i64
+  %array.i.ptr = getelementptr inbounds i32, i32* %array, i64 %i.i64
+  %array.i = load i32, i32* %array.i.ptr, align 4
+  %loop.acc.next = add i32 %loop.acc, %array.i
+  %continue = icmp uge i32 %i, %lowerlimit
+  br i1 %continue, label %loop, label %exit
+
+exit:
+  %result = phi i32 [ 0, %entry ], [ %loop.acc.next, %loop ]
+  ret i32 %result
+}
+
+
+; if we predicated the loop, the guard will definitely fail and we will
+; deoptimize early on.
+define i32 @unsigned_reverse_loop_n_to_1(i32* %array, i32 %length, i32 %n, i32 %lowerlimit) {
+; CHECK-LABEL: @unsigned_reverse_loop_n_to_1(
+entry:
+  %tmp5 = icmp eq i32 %n, 0
+  br i1 %tmp5, label %exit, label %loop.preheader
+
+; CHECK:       loop.preheader:
+; CHECK-NEXT:    [[range_start:%.*]] = add i32 %n, -1
+; CHECK-NEXT:    [[first_iteration_check:%.*]] = icmp ult i32 [[range_start]], %length
+; CHECK-NEXT:    [[wide_cond:%.*]] = and i1 [[first_iteration_check]], false
+loop.preheader:
+  br label %loop
+
+; CHECK: loop:
+; CHECK:    call void (i1, ...) @llvm.experimental.guard(i1 [[wide_cond]], i32 9) [ "deopt"() ]
+loop:
+  %loop.acc = phi i32 [ %loop.acc.next, %loop ], [ 0, %loop.preheader ]
+  %i = phi i32 [ %i.next, %loop ], [ %n, %loop.preheader ]
+  %i.next = add nsw i32 %i, -1
+  %within.bounds = icmp ult i32 %i.next, %length
+  call void (i1, ...) @llvm.experimental.guard(i1 %within.bounds, i32 9) [ "deopt"() ]
+  %i.i64 = zext i32 %i.next to i64
+  %array.i.ptr = getelementptr inbounds i32, i32* %array, i64 %i.i64
+  %array.i = load i32, i32* %array.i.ptr, align 4
+  %loop.acc.next = add i32 %loop.acc, %array.i
+  %continue = icmp uge i32 %i, 1
+  br i1 %continue, label %loop, label %exit
+
+exit:
+  %result = phi i32 [ 0, %entry ], [ %loop.acc.next, %loop ]
+  ret i32 %result
+}
+