diff --git a/llvm/lib/Transforms/Utils/LCSSA.cpp b/llvm/lib/Transforms/Utils/LCSSA.cpp
index 76f2685062698..af79dc456ea6d 100644
--- a/llvm/lib/Transforms/Utils/LCSSA.cpp
+++ b/llvm/lib/Transforms/Utils/LCSSA.cpp
@@ -107,13 +107,15 @@ bool llvm::formLCSSAForInstructions(SmallVectorImpl<Instruction *> &Worklist,
     if (ExitBlocks.empty())
       continue;
 
-    for (Use &U : I->uses()) {
+    for (Use &U : make_early_inc_range(I->uses())) {
       Instruction *User = cast<Instruction>(U.getUser());
       BasicBlock *UserBB = User->getParent();
 
       // Skip uses in unreachable blocks.
-      if (!DT.isReachableFromEntry(UserBB))
+      if (!DT.isReachableFromEntry(UserBB)) {
+        U.set(PoisonValue::get(I->getType()));
         continue;
+      }
 
       // For practical purposes, we consider that the use in a PHI
       // occurs in the respective predecessor block. For more info,
diff --git a/llvm/test/Transforms/LCSSA/unreachable-use.ll b/llvm/test/Transforms/LCSSA/unreachable-use.ll
index 0c70f7a3ef9b8..ea730257daa1a 100644
--- a/llvm/test/Transforms/LCSSA/unreachable-use.ll
+++ b/llvm/test/Transforms/LCSSA/unreachable-use.ll
@@ -42,3 +42,21 @@ bb32:
 bb45:
   unreachable
 }
+
+define void @multiple_unreachable_uses(ptr %A, ptr %B) {
+entry:
+  br label %loop
+
+loop:
+  %gep.A = getelementptr inbounds float, ptr %A, i64 10
+  %gep.B = getelementptr inbounds ptr, ptr %B, i64 20
+  br i1 false, label %exit, label %loop
+
+dead:                 ; No predecessors!
+  %l1 = load float, ptr %gep.A, align 4
+  %l2 = load ptr, ptr %gep.B, align 8
+  br label %exit
+
+exit:
+  ret void
+}
diff --git a/llvm/test/Transforms/LoopVectorize/lcssa-crashes.ll b/llvm/test/Transforms/LoopVectorize/lcssa-crashes.ll
index 6c466540e7089..05d9e027fc223 100644
--- a/llvm/test/Transforms/LoopVectorize/lcssa-crashes.ll
+++ b/llvm/test/Transforms/LoopVectorize/lcssa-crashes.ll
@@ -114,3 +114,54 @@ while.end:
   %add58 = add i32 %inc46, 4
   ret void
 }
+
+; Make sure LV doesn't crash on IR where some LCSSA uses are unreachable.
+define i32 @pr57508(ptr %src) {
+; CHECK-LABEL: @pr57508(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br i1 false, label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
+; CHECK:       vector.ph:
+; CHECK-NEXT:    br label [[VECTOR_BODY:%.*]]
+; CHECK:       vector.body:
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp eq i64 [[INDEX_NEXT]], 2000
+; CHECK-NEXT:    br i1 [[TMP0]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP4:![0-9]+]]
+; CHECK:       middle.block:
+; CHECK-NEXT:    [[CMP_N:%.*]] = icmp eq i64 2001, 2000
+; CHECK-NEXT:    br i1 [[CMP_N]], label [[LOOP_EXIT:%.*]], label [[SCALAR_PH]]
+; CHECK:       scalar.ph:
+; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i64 [ 2000, [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[BC_RESUME_VAL1:%.*]] = phi i32 [ 2000, [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY]] ]
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ [[IV_NEXT:%.*]], [[LOOP]] ], [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ]
+; CHECK-NEXT:    [[LOCAL:%.*]] = phi i32 [ [[LOCAL_NEXT:%.*]], [[LOOP]] ], [ [[BC_RESUME_VAL1]], [[SCALAR_PH]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT:    [[LOCAL_NEXT]] = add i32 [[LOCAL]], 1
+; CHECK-NEXT:    [[EC:%.*]] = icmp eq i64 [[IV]], 2000
+; CHECK-NEXT:    br i1 [[EC]], label [[LOOP_EXIT]], label [[LOOP]], !llvm.loop [[LOOP5:![0-9]+]]
+; CHECK:       loop.exit:
+; CHECK-NEXT:    unreachable
+; CHECK:       bb:
+; CHECK-NEXT:    [[LOCAL_USE:%.*]] = add i32 poison, 1
+; CHECK-NEXT:    ret i32 [[LOCAL_USE]]
+;
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i64 [ %iv.next, %loop ], [ 0, %entry ]
+  %local = phi i32 [ %local.next, %loop ], [ 0, %entry ]
+  %iv.next = add nuw nsw i64 %iv, 1
+  %local.next  = add i32 %local, 1
+  %ec = icmp eq i64 %iv, 2000
+  br i1 %ec, label %loop.exit, label %loop
+
+loop.exit:
+  unreachable
+
+bb:
+  %local.use = add i32 %local, 1
+  ret i32 %local.use
+}