diff --git a/lib/compress.js b/lib/compress.js
index 0f4dd255..45da1e9e 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -48,6 +48,7 @@ function Compressor(options, false_by_default) {
         return new Compressor(options, false_by_default);
     TreeTransformer.call(this, this.before, this.after);
     this.options = defaults(options, {
+        assignments   : false,
         booleans      : !false_by_default,
         cascade       : !false_by_default,
         collapse_vars : !false_by_default,
@@ -484,9 +485,10 @@ merge(Compressor.prototype, {
 
         function is_modified(node, level, immutable) {
             var parent = tw.parent(level);
-            if (is_lhs(node, parent)
-                || !immutable && parent instanceof AST_Call && parent.expression === node) {
+            if (is_lhs(node, parent)) {
                 return true;
+            } else if (parent instanceof AST_Call && parent.expression === node) {
+                return !immutable && level > 0;
             } else if (parent instanceof AST_PropAccess && parent.expression === node) {
                 return !immutable && is_modified(parent, level + 1);
             }
@@ -1144,7 +1146,68 @@ merge(Compressor.prototype, {
                 return true;
             }
         }));
-    };
+    }
+
+    function assign_to_decl(compressor, expr) {
+        if (!(expr instanceof AST_Assign)) return;
+        var def;
+        if (expr.operator == "="
+            && expr.left instanceof AST_SymbolRef
+            && (def = expr.left.definition()).scope === expr.left.scope
+            && (!def.global || compressor.option("toplevel"))
+            && all(def.orig, function(sym) {
+                return sym instanceof AST_SymbolVar;
+            })) {
+            def.references.splice(def.references.indexOf(expr.left), 1);
+            return [ make_node(AST_Var, expr, {
+                definitions: [ make_node(AST_VarDef, expr, {
+                    name: make_node(AST_SymbolVar, expr.left, expr.left),
+                    value: expr.right
+                }) ]
+            }) ];
+        }
+        var body = assign_to_decl(compressor, expr.right);
+        if (body) {
+            if (body.length == 1) {
+                body.push(make_node(AST_SimpleStatement, expr, {
+                    body: make_node(AST_Assign, expr, {
+                        operator: expr.operator,
+                        left: expr.left,
+                        right: expr.right.left
+                    })
+                }));
+            } else {
+                body[1].body = make_node(AST_Assign, expr, {
+                    operator: expr.operator,
+                    left: expr.left,
+                    right: body[1].body
+                });
+            }
+        }
+        return body;
+    }
+
+    function transform_assignments(compressor, expr) {
+        if (!compressor.option("assignments")) return;
+        if (expr instanceof AST_Sequence) {
+            var transformed = false;
+            var list = MAP(expr.expressions, function(e) {
+                var body = assign_to_decl(compressor, e);
+                if (body) {
+                    transformed = true;
+                    return MAP.splice(body);
+                }
+                return e;
+            });
+            if (transformed) {
+                return list.map(function(e) {
+                    return e instanceof AST_Statement ? e : make_node(AST_SimpleStatement, e, {
+                        body: e
+                    });
+                });
+            }
+        } else return assign_to_decl(compressor, expr);
+    }
 
     function is_undefined(node, compressor) {
         return node.is_undefined
@@ -2372,8 +2435,8 @@ merge(Compressor.prototype, {
     });
 
     OPT(AST_SimpleStatement, function(self, compressor){
+        var body = self.body;
         if (compressor.option("side_effects")) {
-            var body = self.body;
             var node = body.drop_side_effect_free(compressor, true);
             if (!node) {
                 compressor.warn("Dropping side-effect-free statement [{file}:{line},{col}]", self.start);
@@ -2383,7 +2446,10 @@ merge(Compressor.prototype, {
                 return make_node(AST_SimpleStatement, self, { body: node });
             }
         }
-        return self;
+        body = transform_assignments(compressor, self.body);
+        return body ? make_node(AST_BlockStatement, self, {
+            body: body
+        }).optimize(compressor) : self;
     });
 
     OPT(AST_DWLoop, function(self, compressor){
@@ -2486,6 +2552,17 @@ merge(Compressor.prototype, {
             }
         }
         if_break_in_loop(self, compressor);
+        if (self.init && !(self.init instanceof AST_Statement)) {
+            var body = transform_assignments(compressor, self.init);
+            if (body) {
+                var node = self.clone();
+                node.init = null;
+                body.push(node);
+                return make_node(AST_BlockStatement, self, {
+                    body: body
+                }).optimize(compressor);
+            }
+        }
         return self;
     });
 
diff --git a/test/compress/collapse_vars.js b/test/compress/collapse_vars.js
index a4c1f9e6..d15a8259 100644
--- a/test/compress/collapse_vars.js
+++ b/test/compress/collapse_vars.js
@@ -505,7 +505,28 @@ collapse_vars_seq: {
     expect: {
         var f1 = function(x, y) {
             var a, b, r = x + y;
-            return a = r * r - r, b = 7, a + b
+            return a = r * r - r, b = 7, a + b;
+        };
+    }
+}
+
+collapse_vars_seq_assignments: {
+    options = {
+        collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
+        comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
+        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, assignments:true
+    }
+    input: {
+        var f1 = function(x, y) {
+            var a, b, r = x + y, q = r * r, z = q - r;
+            a = z, b = 7;
+            return a + b;
+        };
+    }
+    expect: {
+        var f1 = function(x, y) {
+            var r = x + y, b = 7;
+            return r * r - r + b;
         };
     }
 }
@@ -526,7 +547,28 @@ collapse_vars_throw: {
     expect: {
         var f1 = function(x, y) {
             var a, b, r = x + y;
-            throw a = r * r - r, b = 7, a + b
+            throw a = r * r - r, b = 7, a + b;
+        };
+    }
+}
+
+collapse_vars_throw_assignments: {
+    options = {
+        collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
+        comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
+        keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, assignments:true
+    }
+    input: {
+        var f1 = function(x, y) {
+            var a, b, r = x + y, q = r * r, z = q - r;
+            a = z, b = 7;
+            throw a + b;
+        };
+    }
+    expect: {
+        var f1 = function(x,y) {
+            var r = x + y, b = 7;
+            throw r * r - r + b;
         };
     }
 }
@@ -1677,3 +1719,45 @@ var_defs: {
     }
     expect_stdout: "97"
 }
+
+assign_to_var: {
+    options = {
+        assignments: true,
+        collapse_vars: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        function f() {
+            var a;
+            a = x;
+            return a;
+        }
+    }
+    expect: {
+        function f() {
+            return x;
+        }
+    }
+}
+
+issue_27: {
+    options = {
+        assignments: true,
+        collapse_vars: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function(jQuery) {
+            var $;
+            $ = jQuery;
+            $("body").addClass("foo");
+        })(jQuery);
+    }
+    expect: {
+        (function(jQuery) {
+            jQuery("body").addClass("foo");
+        })(jQuery);
+    }
+}
diff --git a/test/compress/reduce_vars.js b/test/compress/reduce_vars.js
index 57e23891..622157c4 100644
--- a/test/compress/reduce_vars.js
+++ b/test/compress/reduce_vars.js
@@ -2327,3 +2327,58 @@ iife_assign: {
     }
     expect_stdout: "1"
 }
+
+assign_to_var: {
+    options = {
+        assignments: true,
+        join_vars: true,
+        loops: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        function f(b) {
+            var a;
+            for (a = x; b;) return a;
+        }
+    }
+    expect: {
+        function f(b) {
+            for (var a = x; b;) return a;
+        }
+    }
+}
+
+issue_315: {
+    options = {
+        assignments: true,
+        evaluate: true,
+        join_vars: true,
+        keep_fargs: false,
+        loops: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(function(s) {
+            var w, _i, _len, _ref, _results;
+            _ref = s.trim().split(" ");
+            _results = [];
+            for (_i = 0, _len = _ref.length; _i < _len; _i++) {
+                w = _ref[_i];
+                _results.push(w.toLowerCase());
+            }
+            return _results;
+        }("test"));
+    }
+    expect: {
+        console.log(function() {
+            for (var _ref = "test".trim().split(" "), _results = [], _i = 0, _len = _ref.length; _i < _len; _i++) {
+                var w = _ref[_i];
+                _results.push(w.toLowerCase());
+            }
+            return _results;
+        }());
+    }
+    expect_stdout: true
+}