Index: lib/Analysis/ScalarEvolution.cpp
===================================================================
--- lib/Analysis/ScalarEvolution.cpp
+++ lib/Analysis/ScalarEvolution.cpp
@@ -10338,6 +10338,29 @@
 bool
 ScalarEvolution::isKnownViaNonRecursiveReasoning(ICmpInst::Predicate Pred,
                                            const SCEV *LHS, const SCEV *RHS) {
+
+  // zext x u<= sext x, sext x s<= zext x
+  switch (Pred) {
+  case ICmpInst::ICMP_SLE: {
+    // If operand >=s 0 then ZExt == SExt.  If operand <s 0 then SExt <u ZExt.
+    const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(LHS);
+    const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(RHS);
+    if (SExt && ZExt && SExt->getOperand() == ZExt->getOperand())
+      return true;
+    break;
+  }
+  case ICmpInst::ICMP_ULE: { 
+    // If operand >=s 0 then ZExt == SExt.  If operand <s 0 then ZExt <u SExt.
+    const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(LHS);
+    const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(RHS);
+    if (SExt && ZExt && SExt->getOperand() == ZExt->getOperand())
+      return true;
+    break;
+  }
+  default:
+    break;
+  };
+
   return isKnownPredicateViaConstantRanges(Pred, LHS, RHS) ||
          IsKnownPredicateViaMinOrMax(*this, Pred, LHS, RHS) ||
          IsKnownPredicateViaAddRecStart(*this, Pred, LHS, RHS) ||
Index: test/Analysis/ScalarEvolution/umin-umax-folds.ll
===================================================================
--- test/Analysis/ScalarEvolution/umin-umax-folds.ll
+++ test/Analysis/ScalarEvolution/umin-umax-folds.ll
@@ -0,0 +1,107 @@
+; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py
+; RUN: opt -analyze -scalar-evolution < %s | FileCheck %s
+
+define void @umin_sext_x_zext_x(i32 %len) {
+; CHECK-LABEL: 'umin_sext_x_zext_x'
+; CHECK-NEXT:  Classifying expressions for: @umin_sext_x_zext_x
+; CHECK-NEXT:    %len.zext = zext i32 %len to i64
+; CHECK-NEXT:    --> (zext i32 %len to i64) U: [0,4294967296) S: [0,4294967296)
+; CHECK-NEXT:    %len.sext = sext i32 %len to i64
+; CHECK-NEXT:    --> (sext i32 %len to i64) U: [-2147483648,2147483648) S: [-2147483648,2147483648)
+; CHECK-NEXT:    %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+; CHECK-NEXT:    --> {0,+,1}<%loop> U: [0,4294967296) S: [0,4294967296) Exits: (zext i32 %len to i64) LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    %iv.next = add i64 %iv, 1
+; CHECK-NEXT:    --> {1,+,1}<%loop> U: [1,4294967297) S: [1,4294967297) Exits: (1 + (zext i32 %len to i64))<nuw><nsw> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    %umin = select i1 %cmp1, i64 %len.zext, i64 %len.sext
+; CHECK-NEXT:    --> (zext i32 %len to i64) U: [0,4294967296) S: [0,4294967296) Exits: (zext i32 %len to i64) LoopDispositions: { %loop: Invariant }
+; CHECK-NEXT:  Determining loop execution counts for: @umin_sext_x_zext_x
+; CHECK-NEXT:  Loop %loop: backedge-taken count is (zext i32 %len to i64)
+; CHECK-NEXT:  Loop %loop: max backedge-taken count is 4294967295
+; CHECK-NEXT:  Loop %loop: Predicated backedge-taken count is (zext i32 %len to i64)
+; CHECK-NEXT:   Predicates:
+; CHECK:       Loop %loop: Trip multiple is 1
+;
+entry:
+  %len.zext = zext i32 %len to i64
+  %len.sext = sext i32 %len to i64
+  br label %loop
+loop:
+  %iv = phi i64 [0, %entry], [%iv.next, %loop]
+  %iv.next = add i64 %iv, 1
+  %cmp1 = icmp ult i64 %len.zext, %len.sext
+  %umin = select i1 %cmp1, i64 %len.zext, i64 %len.sext
+  %cmp2 = icmp ult i64 %iv, %umin
+  br i1 %cmp2, label %loop, label %exit
+exit:
+  ret void
+}
+
+define void @umax_sext_x_zext_x(i32 %len) {
+; CHECK-LABEL: 'umax_sext_x_zext_x'
+; CHECK-NEXT:  Classifying expressions for: @umax_sext_x_zext_x
+; CHECK-NEXT:    %len.zext = zext i32 %len to i64
+; CHECK-NEXT:    --> (zext i32 %len to i64) U: [0,4294967296) S: [0,4294967296)
+; CHECK-NEXT:    %len.sext = sext i32 %len to i64
+; CHECK-NEXT:    --> (sext i32 %len to i64) U: [-2147483648,2147483648) S: [-2147483648,2147483648)
+; CHECK-NEXT:    %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+; CHECK-NEXT:    --> {0,+,1}<%loop> U: full-set S: full-set Exits: (sext i32 %len to i64) LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    %iv.next = add i64 %iv, 1
+; CHECK-NEXT:    --> {1,+,1}<%loop> U: full-set S: full-set Exits: (1 + (sext i32 %len to i64))<nsw> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    %umax = select i1 %cmp1, i64 %len.zext, i64 %len.sext
+; CHECK-NEXT:    --> (sext i32 %len to i64) U: [-2147483648,2147483648) S: [-2147483648,2147483648) Exits: (sext i32 %len to i64) LoopDispositions: { %loop: Invariant }
+; CHECK-NEXT:  Determining loop execution counts for: @umax_sext_x_zext_x
+; CHECK-NEXT:  Loop %loop: backedge-taken count is (sext i32 %len to i64)
+; CHECK-NEXT:  Loop %loop: max backedge-taken count is -1
+; CHECK-NEXT:  Loop %loop: Predicated backedge-taken count is (sext i32 %len to i64)
+; CHECK-NEXT:   Predicates:
+; CHECK:       Loop %loop: Trip multiple is 1
+;
+entry:
+  %len.zext = zext i32 %len to i64
+  %len.sext = sext i32 %len to i64
+  br label %loop
+loop:
+  %iv = phi i64 [0, %entry], [%iv.next, %loop]
+  %iv.next = add i64 %iv, 1
+  %cmp1 = icmp ugt i64 %len.zext, %len.sext
+  %umax = select i1 %cmp1, i64 %len.zext, i64 %len.sext
+  %cmp2 = icmp ult i64 %iv, %umax
+  br i1 %cmp2, label %loop, label %exit
+exit:
+  ret void
+}
+
+define void @umin_sext_x_zext_x_2(i32 %len) {
+; CHECK-LABEL: 'umin_sext_x_zext_x_2'
+; CHECK-NEXT:  Classifying expressions for: @umin_sext_x_zext_x_2
+; CHECK-NEXT:    %len.zext = zext i32 %len to i64
+; CHECK-NEXT:    --> (zext i32 %len to i64) U: [0,4294967296) S: [0,4294967296)
+; CHECK-NEXT:    %len.sext = sext i32 %len to i64
+; CHECK-NEXT:    --> (sext i32 %len to i64) U: [-2147483648,2147483648) S: [-2147483648,2147483648)
+; CHECK-NEXT:    %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+; CHECK-NEXT:    --> {0,+,1}<%loop> U: [0,4294967296) S: [0,4294967296) Exits: (zext i32 %len to i64) LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    %iv.next = add i64 %iv, 1
+; CHECK-NEXT:    --> {1,+,1}<%loop> U: [1,4294967297) S: [1,4294967297) Exits: (1 + (zext i32 %len to i64))<nuw><nsw> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    %and = and i1 %cmp1, %cmp2
+; CHECK-NEXT:    --> %and U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Variant }
+; CHECK-NEXT:  Determining loop execution counts for: @umin_sext_x_zext_x_2
+; CHECK-NEXT:  Loop %loop: backedge-taken count is (zext i32 %len to i64)
+; CHECK-NEXT:  Loop %loop: max backedge-taken count is 4294967295
+; CHECK-NEXT:  Loop %loop: Predicated backedge-taken count is (zext i32 %len to i64)
+; CHECK-NEXT:   Predicates:
+; CHECK:       Loop %loop: Trip multiple is 1
+;
+entry:
+  %len.zext = zext i32 %len to i64
+  %len.sext = sext i32 %len to i64
+  br label %loop
+loop:
+  %iv = phi i64 [0, %entry], [%iv.next, %loop]
+  %iv.next = add i64 %iv, 1
+  %cmp1 = icmp ult i64 %iv, %len.zext
+  %cmp2 = icmp ult i64 %iv, %len.sext
+  %and = and i1 %cmp1, %cmp2
+  br i1 %and, label %loop, label %exit
+exit:
+  ret void
+}