diff --git a/src/passes/OptimizeInstructions.cpp b/src/passes/OptimizeInstructions.cpp
index e388775caab..1574fd0a160 100644
--- a/src/passes/OptimizeInstructions.cpp
+++ b/src/passes/OptimizeInstructions.cpp
@@ -1193,6 +1193,28 @@ struct OptimizeInstructions
           BranchHints::flip(curr, getFunction());
         }
       }
+      // (i32.and X 1) as if-else condition =>  (i32.ctz X) with swapped arms,
+      // since ctz(X) == 0  iff  LSB(X) == 1  (saves one instruction).
+      if (auto* binary = curr->condition->dynCast<Binary>()) {
+        if (binary->op == AndInt32) {
+          Expression* other = nullptr;
+          if (auto* c = binary->right->dynCast<Const>()) {
+            if (c->value.geti32() == 1) {
+              other = binary->left;
+            }
+          } else if (auto* c = binary->left->dynCast<Const>()) {
+            if (c->value.geti32() == 1) {
+              other = binary->right;
+            }
+          }
+          if (other) {
+            Builder builder(*getModule());
+            curr->condition = builder.makeUnary(CtzInt32, other);
+            std::swap(curr->ifTrue, curr->ifFalse);
+            BranchHints::flip(curr, getFunction());
+          }
+        }
+      }
       // Note that we do not consider metadata here. Like LLVM, we ignore
       // metadata when trying to fold code together, preferring certain
       // optimization over possible benefits of profiling data.
@@ -3114,6 +3136,24 @@ struct OptimizeInstructions
               binary->op = op;
               return binary;
             }
+            // eqz(and X 1) ==> ctz X  in boolean context:
+            // both are truthy iff LSB(X) == 0, saving one instruction.
+            if (binary->op == AndInt32) {
+              Expression* other = nullptr;
+              if (auto* c = binary->right->dynCast<Const>()) {
+                if (c->value.geti32() == 1) {
+                  other = binary->left;
+                }
+              } else if (auto* c = binary->left->dynCast<Const>()) {
+                if (c->value.geti32() == 1) {
+                  other = binary->right;
+                }
+              }
+              if (other) {
+                Builder builder(*getModule());
+                return builder.makeUnary(CtzInt32, other);
+              }
+            }
           }
         }
         if (unary->op == EqZInt32 || unary->op == EqZInt64) {
diff --git a/test/lit/passes/optimize-instructions-lsb-if.wast b/test/lit/passes/optimize-instructions-lsb-if.wast
new file mode 100644
index 00000000000..fbd6eca3179
--- /dev/null
+++ b/test/lit/passes/optimize-instructions-lsb-if.wast
@@ -0,0 +1,79 @@
+;; NOTE: Assertions have been generated by update_lit_checks.py and should not be edited.
+;; RUN: wasm-opt %s --optimize-instructions -S -o - | filecheck %s
+
+;; Test that (if (i32.and X (i32.const 1)) T E) is optimized to
+;; (if (i32.ctz X) E T), and (br_if N V (i32.eqz (i32.and X 1))) to
+;; (br_if N V (i32.ctz X)), saving one instruction in each case.
+
+(module
+  ;; CHECK:      (func $lsb-if (param $x i32) (result i32)
+  ;; CHECK-NEXT:  (if (result i32)
+  ;; CHECK-NEXT:   (i32.ctz
+  ;; CHECK-NEXT:    (local.get $x)
+  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:   (then
+  ;; CHECK-NEXT:    (i32.const 0)
+  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:   (else
+  ;; CHECK-NEXT:    (i32.const 1)
+  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT: )
+  (func $lsb-if (param $x i32) (result i32)
+    ;; if LSB is set, return 1; else return 0
+    ;; optimizes to: if ctz(x) != 0, return 0; else return 1
+    (if (result i32)
+      (i32.and (local.get $x) (i32.const 1))
+      (then (i32.const 1))
+      (else (i32.const 0))
+    )
+  )
+
+  ;; CHECK:      (func $lsb-if-const-left (param $x i32) (result i32)
+  ;; CHECK-NEXT:  (if (result i32)
+  ;; CHECK-NEXT:   (i32.ctz
+  ;; CHECK-NEXT:    (local.get $x)
+  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:   (then
+  ;; CHECK-NEXT:    (i32.const 0)
+  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:   (else
+  ;; CHECK-NEXT:    (i32.const 1)
+  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT: )
+  (func $lsb-if-const-left (param $x i32) (result i32)
+    ;; same but constant on the left
+    (if (result i32)
+      (i32.and (i32.const 1) (local.get $x))
+      (then (i32.const 1))
+      (else (i32.const 0))
+    )
+  )
+
+  ;; CHECK:      (func $lsb-brif (param $x i32) (result i32)
+  ;; CHECK-NEXT:  (block $done (result i32)
+  ;; CHECK-NEXT:   (drop
+  ;; CHECK-NEXT:    (br_if $done
+  ;; CHECK-NEXT:     (i32.const 99)
+  ;; CHECK-NEXT:     (i32.ctz
+  ;; CHECK-NEXT:      (local.get $x)
+  ;; CHECK-NEXT:     )
+  ;; CHECK-NEXT:    )
+  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:   (i32.const 42)
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT: )
+  (func $lsb-brif (param $x i32) (result i32)
+    ;; br_if (eqz (and X 1)) => br_if (ctz X): the typical is_skewed/is_scalar pattern
+    (block $done (result i32)
+      (drop
+        (br_if $done
+          (i32.const 99)
+          (i32.eqz (i32.and (local.get $x) (i32.const 1)))
+        )
+      )
+      (i32.const 42)
+    )
+  )
+)