diff --git a/src/codegen/c.zig b/src/codegen/c.zig
index c306e0a6b0..b814be4445 100644
--- a/src/codegen/c.zig
+++ b/src/codegen/c.zig
@@ -1000,6 +1000,46 @@ pub const DeclGen = struct {
         return name;
     }
 
+    fn renderTupleTypedef(dg: *DeclGen, t: Type) error{ OutOfMemory, AnalysisFail }![]const u8 {
+        const tuple = t.tupleFields();
+
+        var buffer = std.ArrayList(u8).init(dg.typedefs.allocator);
+        defer buffer.deinit();
+        const writer = buffer.writer();
+
+        try buffer.appendSlice("typedef struct {\n");
+        {
+            for (tuple.types) |field_ty, i| {
+                const val = tuple.values[i];
+                if (val.tag() != .unreachable_value) continue;
+
+                var name = std.ArrayList(u8).init(dg.gpa);
+                defer name.deinit();
+                try name.writer().print("field_{d}", .{i});
+
+                try buffer.append(' ');
+                try dg.renderTypeAndName(writer, field_ty, .{ .bytes = name.items }, .Mut, Value.initTag(.abi_align_default));
+                try buffer.appendSlice(";\n");
+            }
+        }
+        try buffer.appendSlice("} ");
+
+        const name_start = buffer.items.len;
+        try writer.print("zig_T_{};\n", .{typeToCIdentifier(t)});
+
+        const rendered = buffer.toOwnedSlice();
+        errdefer dg.typedefs.allocator.free(rendered);
+        const name = rendered[name_start .. rendered.len - 2];
+
+        try dg.typedefs.ensureUnusedCapacity(1);
+        dg.typedefs.putAssumeCapacityNoClobber(
+            try t.copy(dg.typedefs_arena),
+            .{ .name = name, .rendered = rendered },
+        );
+
+        return name;
+    }
+
     fn renderUnionTypedef(dg: *DeclGen, t: Type) error{ OutOfMemory, AnalysisFail }![]const u8 {
         const union_ty = t.cast(Type.Payload.Union).?.data;
         const fqn = try union_ty.getFullyQualifiedName(dg.typedefs.allocator);
@@ -1276,7 +1316,9 @@ pub const DeclGen = struct {
                 return w.writeAll(name);
             },
             .Struct => {
-                const name = dg.getTypedefName(t) orelse
+                const name = dg.getTypedefName(t) orelse if (t.isTuple())
+                    try dg.renderTupleTypedef(t)
+                else
                     try dg.renderStructTypedef(t);
 
                 return w.writeAll(name);
@@ -3116,6 +3158,8 @@ fn structFieldPtr(f: *Function, inst: Air.Inst.Index, struct_ptr_ty: Type, struc
     var field_name: []const u8 = undefined;
     var field_val_ty: Type = undefined;
 
+    var buf = std.ArrayList(u8).init(f.object.dg.gpa);
+    defer buf.deinit();
     switch (struct_ty.tag()) {
         .@"struct" => {
             const fields = struct_ty.structFields();
@@ -3127,6 +3171,14 @@ fn structFieldPtr(f: *Function, inst: Air.Inst.Index, struct_ptr_ty: Type, struc
             field_name = fields.keys()[index];
             field_val_ty = fields.values()[index].ty;
         },
+        .tuple => {
+            const tuple = struct_ty.tupleFields();
+            if (tuple.values[index].tag() != .unreachable_value) return CValue.none;
+
+            try buf.writer().print("field_{d}", .{index});
+            field_name = buf.items;
+            field_val_ty = tuple.types[index];
+        },
         else => unreachable,
     }
     const payload = if (struct_ty.tag() == .union_tagged) "payload." else "";
@@ -3149,9 +3201,18 @@ fn airStructFieldVal(f: *Function, inst: Air.Inst.Index) !CValue {
     const writer = f.object.writer();
     const struct_byval = try f.resolveInst(extra.struct_operand);
     const struct_ty = f.air.typeOf(extra.struct_operand);
+    var buf = std.ArrayList(u8).init(f.object.dg.gpa);
+    defer buf.deinit();
     const field_name = switch (struct_ty.tag()) {
         .@"struct" => struct_ty.structFields().keys()[extra.field_index],
         .@"union", .union_tagged => struct_ty.unionFields().keys()[extra.field_index],
+        .tuple => blk: {
+            const tuple = struct_ty.tupleFields();
+            if (tuple.values[extra.field_index].tag() != .unreachable_value) return CValue.none;
+
+            try buf.writer().print("field_{d}", .{extra.field_index});
+            break :blk buf.items;
+        },
         else => unreachable,
     };
     const payload = if (struct_ty.tag() == .union_tagged) "payload." else "";
@@ -3652,11 +3713,25 @@ fn airAggregateInit(f: *Function, inst: Air.Inst.Index) !CValue {
 
     const writer = f.object.writer();
     const local = try f.allocLocal(inst_ty, .Const);
-    try writer.writeAll(" = ");
+    try writer.writeAll(" = {");
+    switch (vector_ty.zigTypeTag()) {
+        .Struct => {
+            const tuple = vector_ty.tupleFields();
+            var i: usize = 0;
+            for (elements) |elem, elem_index| {
+                if (tuple.values[elem_index].tag() != .unreachable_value) continue;
 
-    _ = elements;
-    _ = local;
-    return f.fail("TODO: C backend: implement airAggregateInit", .{});
+                const value = try f.resolveInst(elem);
+                if (i != 0) try writer.writeAll(", ");
+                try f.writeCValue(writer, value);
+                i += 1;
+            }
+        },
+        else => |tag| return f.fail("TODO: C backend: implement airAggregateInit for type {s}", .{@tagName(tag)}),
+    }
+    try writer.writeAll("};\n");
+
+    return local;
 }
 
 fn airUnionInit(f: *Function, inst: Air.Inst.Index) !CValue {
diff --git a/test/behavior.zig b/test/behavior.zig
index f6ff8bd64d..4775767ac3 100644
--- a/test/behavior.zig
+++ b/test/behavior.zig
@@ -146,6 +146,7 @@ test {
     {
         // Tests that pass for stage1, llvm backend, C backend
         _ = @import("behavior/bugs/421.zig");
+        _ = @import("behavior/bugs/3779.zig");
         _ = @import("behavior/bugs/9584.zig");
         _ = @import("behavior/cast_int.zig");
         _ = @import("behavior/eval.zig");
@@ -162,7 +163,6 @@ test {
             _ = @import("behavior/saturating_arithmetic.zig");
             _ = @import("behavior/widening.zig");
             _ = @import("behavior/bugs/2114.zig");
-            _ = @import("behavior/bugs/3779.zig");
             _ = @import("behavior/bugs/10147.zig");
             _ = @import("behavior/shuffle.zig");
 
diff --git a/test/behavior/bugs/3779.zig b/test/behavior/bugs/3779.zig
index 51b1725dd9..7dd0914161 100644
--- a/test/behavior/bugs/3779.zig
+++ b/test/behavior/bugs/3779.zig
@@ -7,9 +7,9 @@ const ptr_tag_name: [*:0]const u8 = tag_name;
 
 test "@tagName() returns a string literal" {
     if (builtin.zig_backend == .stage1) return error.SkipZigTest; // stage1 gets the type wrong
-    try std.testing.expectEqual(*const [13:0]u8, @TypeOf(tag_name));
-    try std.testing.expectEqualStrings("TestEnumValue", tag_name);
-    try std.testing.expectEqualStrings("TestEnumValue", ptr_tag_name[0..tag_name.len]);
+    try std.testing.expect(*const [13:0]u8 == @TypeOf(tag_name));
+    try std.testing.expect(std.mem.eql(u8, "TestEnumValue", tag_name));
+    try std.testing.expect(std.mem.eql(u8, "TestEnumValue", ptr_tag_name[0..tag_name.len]));
 }
 
 const TestError = error{TestErrorCode};
@@ -18,9 +18,9 @@ const ptr_error_name: [*:0]const u8 = error_name;
 
 test "@errorName() returns a string literal" {
     if (builtin.zig_backend == .stage1) return error.SkipZigTest; // stage1 gets the type wrong
-    try std.testing.expectEqual(*const [13:0]u8, @TypeOf(error_name));
-    try std.testing.expectEqualStrings("TestErrorCode", error_name);
-    try std.testing.expectEqualStrings("TestErrorCode", ptr_error_name[0..error_name.len]);
+    try std.testing.expect(*const [13:0]u8 == @TypeOf(error_name));
+    try std.testing.expect(std.mem.eql(u8, "TestErrorCode", error_name));
+    try std.testing.expect(std.mem.eql(u8, "TestErrorCode", ptr_error_name[0..error_name.len]));
 }
 
 const TestType = struct {};
@@ -29,9 +29,9 @@ const ptr_type_name: [*:0]const u8 = type_name;
 
 test "@typeName() returns a string literal" {
     if (builtin.zig_backend == .stage1) return error.SkipZigTest; // stage1 gets the type wrong
-    try std.testing.expectEqual(*const [type_name.len:0]u8, @TypeOf(type_name));
-    try std.testing.expectEqualStrings("behavior.bugs.3779.TestType", type_name);
-    try std.testing.expectEqualStrings("behavior.bugs.3779.TestType", ptr_type_name[0..type_name.len]);
+    try std.testing.expect(*const [type_name.len:0]u8 == @TypeOf(type_name));
+    try std.testing.expect(std.mem.eql(u8, "behavior.bugs.3779.TestType", type_name));
+    try std.testing.expect(std.mem.eql(u8, "behavior.bugs.3779.TestType", ptr_type_name[0..type_name.len]));
 }
 
 const actual_contents = @embedFile("3779_file_to_embed.txt");
@@ -39,10 +39,10 @@ const ptr_actual_contents: [*:0]const u8 = actual_contents;
 const expected_contents = "hello zig\n";
 
 test "@embedFile() returns a string literal" {
-    try std.testing.expectEqual(*const [expected_contents.len:0]u8, @TypeOf(actual_contents));
+    try std.testing.expect(*const [expected_contents.len:0]u8 == @TypeOf(actual_contents));
     try std.testing.expect(std.mem.eql(u8, expected_contents, actual_contents));
-    try std.testing.expectEqualStrings(expected_contents, actual_contents);
-    try std.testing.expectEqualStrings(expected_contents, ptr_actual_contents[0..actual_contents.len]);
+    try std.testing.expect(std.mem.eql(u8, expected_contents, actual_contents));
+    try std.testing.expect(std.mem.eql(u8, expected_contents, ptr_actual_contents[0..actual_contents.len]));
 }
 
 fn testFnForSrc() std.builtin.SourceLocation {
@@ -51,9 +51,9 @@ fn testFnForSrc() std.builtin.SourceLocation {
 
 test "@src() returns a struct containing 0-terminated string slices" {
     const src = testFnForSrc();
-    try std.testing.expectEqual([:0]const u8, @TypeOf(src.file));
+    try std.testing.expect([:0]const u8 == @TypeOf(src.file));
     try std.testing.expect(std.mem.endsWith(u8, src.file, "3779.zig"));
-    try std.testing.expectEqual([:0]const u8, @TypeOf(src.fn_name));
+    try std.testing.expect([:0]const u8 == @TypeOf(src.fn_name));
     try std.testing.expect(std.mem.endsWith(u8, src.fn_name, "testFnForSrc"));
 
     const ptr_src_file: [*:0]const u8 = src.file;
diff --git a/test/behavior/tuple.zig b/test/behavior/tuple.zig
index 6f9522834e..71bf52d71e 100644
--- a/test/behavior/tuple.zig
+++ b/test/behavior/tuple.zig
@@ -2,11 +2,9 @@ const builtin = @import("builtin");
 const std = @import("std");
 const testing = std.testing;
 const expect = testing.expect;
-const expectEqual = testing.expectEqual;
 
 test "tuple concatenation" {
     if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest; // TODO
-    if (builtin.zig_backend == .stage2_c) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
@@ -18,8 +16,8 @@ test "tuple concatenation" {
             var x = .{a};
             var y = .{b};
             var c = x ++ y;
-            try expectEqual(@as(i32, 1), c[0]);
-            try expectEqual(@as(i32, 2), c[1]);
+            try expect(@as(i32, 1) == c[0]);
+            try expect(@as(i32, 2) == c[1]);
         }
     };
     try S.doTheTest();
@@ -51,7 +49,6 @@ test "tuple multiplication" {
 
 test "more tuple concatenation" {
     if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest; // TODO
-    if (builtin.zig_backend == .stage2_c) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
@@ -129,7 +126,6 @@ test "tuple initializer for var" {
 }
 
 test "array-like initializer for tuple types" {
-    if (builtin.zig_backend == .stage2_c) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO