diff --git a/lib/std/zig/render.zig b/lib/std/zig/render.zig
index ce63c08533..348b75159f 100644
--- a/lib/std/zig/render.zig
+++ b/lib/std/zig/render.zig
@@ -26,6 +26,9 @@ pub const Fixups = struct {
     omit_nodes: std.AutoHashMapUnmanaged(Ast.Node.Index, void) = .{},
     /// These expressions will be replaced with the string value.
     replace_nodes: std.AutoHashMapUnmanaged(Ast.Node.Index, []const u8) = .{},
+    /// Change all identifier names matching the key to be value instead.
+    rename_identifiers: std.StringArrayHashMapUnmanaged([]const u8) = .{},
+
     /// All `@import` builtin calls which refer to a file path will be prefixed
     /// with this path.
     rebase_imported_paths: ?[]const u8 = null,
@@ -34,7 +37,9 @@ pub const Fixups = struct {
         return f.unused_var_decls.count() +
             f.gut_functions.count() +
             f.omit_nodes.count() +
-            f.replace_nodes.count();
+            f.replace_nodes.count() +
+            f.rename_identifiers.count() +
+            @intFromBool(f.rebase_imported_paths != null);
     }
 
     pub fn clearRetainingCapacity(f: *Fixups) void {
@@ -42,6 +47,9 @@ pub const Fixups = struct {
         f.gut_functions.clearRetainingCapacity();
         f.omit_nodes.clearRetainingCapacity();
         f.replace_nodes.clearRetainingCapacity();
+        f.rename_identifiers.clearRetainingCapacity();
+
+        f.rebase_imported_paths = null;
     }
 
     pub fn deinit(f: *Fixups, gpa: Allocator) void {
@@ -49,6 +57,7 @@ pub const Fixups = struct {
         f.gut_functions.deinit(gpa);
         f.omit_nodes.deinit(gpa);
         f.replace_nodes.deinit(gpa);
+        f.rename_identifiers.deinit(gpa);
         f.* = undefined;
     }
 };
@@ -2833,6 +2842,13 @@ fn renderIdentifier(r: *Render, token_index: Ast.TokenIndex, space: Space, quote
     const token_tags = tree.tokens.items(.tag);
     assert(token_tags[token_index] == .identifier);
     const lexeme = tokenSliceForRender(tree, token_index);
+
+    if (r.fixups.rename_identifiers.get(lexeme)) |mangled| {
+        try r.ais.writer().writeAll(mangled);
+        try renderSpace(r, token_index, lexeme.len, space);
+        return;
+    }
+
     if (lexeme[0] != '@') {
         return renderToken(r, token_index, space);
     }
diff --git a/src/reduce.zig b/src/reduce.zig
index 82e4bc9031..d8af4dddc3 100644
--- a/src/reduce.zig
+++ b/src/reduce.zig
@@ -148,7 +148,7 @@ pub fn main(gpa: Allocator, arena: Allocator, args: []const []const u8) !void {
 
     var transformations = std.ArrayList(Walk.Transformation).init(gpa);
     defer transformations.deinit();
-    try Walk.findTransformations(&tree, &transformations);
+    try Walk.findTransformations(arena, &tree, &transformations);
     sortTransformations(transformations.items, rng.random());
 
     fresh: while (transformations.items.len > 0) {
@@ -162,12 +162,19 @@ pub fn main(gpa: Allocator, arena: Allocator, args: []const []const u8) !void {
             subset_size = @max(1, subset_size / 2);
 
             const this_set = transformations.items[start_index..][0..subset_size];
+            std.debug.print("trying {d} random transformations: ", .{subset_size});
+            for (this_set[0..@min(this_set.len, 20)]) |t| {
+                std.debug.print("{s} ", .{@tagName(t)});
+            }
+            std.debug.print("\n", .{});
             try transformationsToFixups(gpa, arena, root_source_file_path, this_set, &fixups);
 
             rendered.clearRetainingCapacity();
             try tree.renderToArrayList(&rendered, fixups);
             try std.fs.cwd().writeFile(root_source_file_path, rendered.items);
 
+            //std.debug.print("trying this code:\n{s}\n", .{rendered.items});
+
             const interestingness = try runCheck(arena, interestingness_argv.items);
             std.debug.print("{d} random transformations: {s}. {d} remaining\n", .{
                 subset_size, @tagName(interestingness), transformations.items.len - start_index,
@@ -179,7 +186,7 @@ pub fn main(gpa: Allocator, arena: Allocator, args: []const []const u8) !void {
                     tree.deinit(gpa);
                     tree = new_tree;
 
-                    try Walk.findTransformations(&tree, &transformations);
+                    try Walk.findTransformations(arena, &tree, &transformations);
                     // Resetting based on the seed again means we will get the same
                     // results if restarting the reduction process from this new point.
                     rng = std.rand.DefaultPrng.init(seed);
@@ -263,7 +270,6 @@ fn transformationsToFixups(
             try fixups.replace_nodes.put(gpa, node, "undefined");
         },
         .inline_imported_file => |inline_imported_file| {
-            defer gpa.free(inline_imported_file.imported_string);
             const full_imported_path = try std.fs.path.join(gpa, &.{
                 std.fs.path.dirname(root_source_file_path) orelse ".",
                 inline_imported_file.imported_string,
@@ -274,14 +280,34 @@ fn transformationsToFixups(
                 gpa.free(other_file_ast.source);
                 other_file_ast.deinit(gpa);
             }
-            var other_source = std.ArrayList(u8).init(gpa);
-            defer other_source.deinit();
+
             var inlined_fixups: Ast.Fixups = .{};
             defer inlined_fixups.deinit(gpa);
+            if (std.fs.path.dirname(inline_imported_file.imported_string)) |dirname| {
+                inlined_fixups.rebase_imported_paths = dirname;
+            }
+            for (inline_imported_file.in_scope_names.keys()) |name| {
+                // This name needs to be mangled in order to not cause an
+                // ambiguous reference error.
+                var i: u32 = 2;
+                const mangled = while (true) : (i += 1) {
+                    const mangled = try std.fmt.allocPrint(gpa, "{s}{d}", .{ name, i });
+                    if (!inline_imported_file.in_scope_names.contains(mangled))
+                        break mangled;
+                    gpa.free(mangled);
+                };
+                try inlined_fixups.rename_identifiers.put(gpa, name, mangled);
+            }
+            defer {
+                for (inlined_fixups.rename_identifiers.values()) |v| {
+                    gpa.free(v);
+                }
+            }
+
+            var other_source = std.ArrayList(u8).init(gpa);
+            defer other_source.deinit();
             try other_source.appendSlice("struct {\n");
-            try other_file_ast.renderToArrayList(&other_source, .{
-                .rebase_imported_paths = std.fs.path.dirname(inline_imported_file.imported_string),
-            });
+            try other_file_ast.renderToArrayList(&other_source, inlined_fixups);
             try other_source.appendSlice("}");
 
             try fixups.replace_nodes.put(
diff --git a/src/reduce/Walk.zig b/src/reduce/Walk.zig
index c68e58a4fa..d62cc4e905 100644
--- a/src/reduce/Walk.zig
+++ b/src/reduce/Walk.zig
@@ -7,7 +7,9 @@ const BuiltinFn = @import("../BuiltinFn.zig");
 ast: *const Ast,
 transformations: *std.ArrayList(Transformation),
 unreferenced_globals: std.StringArrayHashMapUnmanaged(Ast.Node.Index),
+in_scope_names: std.StringArrayHashMapUnmanaged(u32),
 gpa: std.mem.Allocator,
+arena: std.mem.Allocator,
 
 pub const Transformation = union(enum) {
     /// Replace the fn decl AST Node with one whose body is only `@trap()` with
@@ -18,25 +20,39 @@ pub const Transformation = union(enum) {
     /// Replace an expression with `undefined`.
     replace_with_undef: Ast.Node.Index,
     /// Replace an `@import` with the imported file contents wrapped in a struct.
-    inline_imported_file: struct {
+    inline_imported_file: InlineImportedFile,
+
+    pub const InlineImportedFile = struct {
         builtin_call_node: Ast.Node.Index,
         imported_string: []const u8,
-    },
+        /// Identifier names that must be renamed in the inlined code or else
+        /// will cause ambiguous reference errors.
+        in_scope_names: std.StringArrayHashMapUnmanaged(void),
+    };
 };
 
 pub const Error = error{OutOfMemory};
 
 /// The result will be priority shuffled.
-pub fn findTransformations(ast: *const Ast, transformations: *std.ArrayList(Transformation)) !void {
+pub fn findTransformations(
+    arena: std.mem.Allocator,
+    ast: *const Ast,
+    transformations: *std.ArrayList(Transformation),
+) !void {
     transformations.clearRetainingCapacity();
 
     var walk: Walk = .{
         .ast = ast,
         .transformations = transformations,
         .gpa = transformations.allocator,
+        .arena = arena,
         .unreferenced_globals = .{},
+        .in_scope_names = .{},
     };
-    defer walk.unreferenced_globals.deinit(walk.gpa);
+    defer {
+        walk.unreferenced_globals.deinit(walk.gpa);
+        walk.in_scope_names.deinit(walk.gpa);
+    }
 
     try walkMembers(&walk, walk.ast.rootDecls());
 
@@ -49,14 +65,18 @@ pub fn findTransformations(ast: *const Ast, transformations: *std.ArrayList(Tran
 
 fn walkMembers(w: *Walk, members: []const Ast.Node.Index) Error!void {
     // First we scan for globals so that we can delete them while walking.
-    try scanDecls(w, members);
+    try scanDecls(w, members, .add);
 
     for (members) |member| {
         try walkMember(w, member);
     }
+
+    try scanDecls(w, members, .remove);
 }
 
-fn scanDecls(w: *Walk, members: []const Ast.Node.Index) Error!void {
+const ScanDeclsAction = enum { add, remove };
+
+fn scanDecls(w: *Walk, members: []const Ast.Node.Index, action: ScanDeclsAction) Error!void {
     const ast = w.ast;
     const gpa = w.gpa;
     const node_tags = ast.nodes.items(.tag);
@@ -80,9 +100,27 @@ fn scanDecls(w: *Walk, members: []const Ast.Node.Index) Error!void {
 
             else => continue,
         };
+
         assert(token_tags[name_token] == .identifier);
         const name_bytes = ast.tokenSlice(name_token);
-        try w.unreferenced_globals.put(gpa, name_bytes, member_node);
+
+        switch (action) {
+            .add => {
+                try w.unreferenced_globals.put(gpa, name_bytes, member_node);
+
+                const gop = try w.in_scope_names.getOrPut(gpa, name_bytes);
+                if (!gop.found_existing) gop.value_ptr.* = 0;
+                gop.value_ptr.* += 1;
+            },
+            .remove => {
+                const entry = w.in_scope_names.getEntry(name_bytes).?;
+                if (entry.value_ptr.* <= 1) {
+                    assert(w.in_scope_names.swapRemove(name_bytes));
+                } else {
+                    entry.value_ptr.* -= 1;
+                }
+            },
+        }
     }
 }
 
@@ -567,12 +605,12 @@ fn walkLocalVarDecl(w: *Walk, var_decl: Ast.full.VarDecl) Error!void {
         try walkExpression(w, var_decl.ast.section_node);
     }
 
-    assert(var_decl.ast.init_node != 0);
-    if (!isUndefinedIdent(w.ast, var_decl.ast.init_node)) {
-        try w.transformations.append(.{ .replace_with_undef = var_decl.ast.init_node });
+    if (var_decl.ast.init_node != 0) {
+        if (!isUndefinedIdent(w.ast, var_decl.ast.init_node)) {
+            try w.transformations.append(.{ .replace_with_undef = var_decl.ast.init_node });
+        }
+        try walkExpression(w, var_decl.ast.init_node);
     }
-
-    return walkExpression(w, var_decl.ast.init_node);
 }
 
 fn walkContainerField(w: *Walk, field: Ast.full.ContainerField) Error!void {
@@ -582,7 +620,9 @@ fn walkContainerField(w: *Walk, field: Ast.full.ContainerField) Error!void {
     if (field.ast.align_expr != 0) {
         try walkExpression(w, field.ast.align_expr); // alignment
     }
-    try walkExpression(w, field.ast.value_expr); // value
+    if (field.ast.value_expr != 0) {
+        try walkExpression(w, field.ast.value_expr); // value
+    }
 }
 
 fn walkBlock(
@@ -690,7 +730,6 @@ fn walkBuiltinCall(
     params: []const Ast.Node.Index,
 ) Error!void {
     const ast = w.ast;
-    const gpa = w.gpa;
     const main_tokens = ast.nodes.items(.main_token);
     const builtin_token = main_tokens[call_node];
     const builtin_name = ast.tokenSlice(builtin_token);
@@ -700,12 +739,17 @@ fn walkBuiltinCall(
             const operand_node = params[0];
             const str_lit_token = main_tokens[operand_node];
             const token_bytes = ast.tokenSlice(str_lit_token);
-            const imported_string = std.zig.string_literal.parseAlloc(gpa, token_bytes) catch
-                unreachable;
-            if (std.mem.endsWith(u8, imported_string, ".zig")) {
+            if (std.mem.endsWith(u8, token_bytes, ".zig\"")) {
+                const imported_string = std.zig.string_literal.parseAlloc(w.arena, token_bytes) catch
+                    unreachable;
                 try w.transformations.append(.{ .inline_imported_file = .{
                     .builtin_call_node = call_node,
                     .imported_string = imported_string,
+                    .in_scope_names = try std.StringArrayHashMapUnmanaged(void).init(
+                        w.arena,
+                        w.in_scope_names.keys(),
+                        &.{},
+                    ),
                 } });
             }
         },