diff --git a/lib/std/Uri.zig b/lib/std/Uri.zig
index 933fcfb657..0903c129c4 100644
--- a/lib/std/Uri.zig
+++ b/lib/std/Uri.zig
@@ -342,7 +342,7 @@ pub fn format(
 /// The return value will contain unescaped strings pointing into the
 /// original `text`. Each component that is provided, will be non-`null`.
 pub fn parse(text: []const u8) ParseError!Uri {
-    var reader = SliceReader{ .slice = text };
+    var reader: SliceReader = .{ .slice = text };
     const scheme = reader.readWhile(isSchemeChar);
 
     // after the scheme, a ':' must appear
@@ -359,111 +359,145 @@ pub fn parse(text: []const u8) ParseError!Uri {
     return uri;
 }
 
-/// Implementation of RFC 3986, Section 5.2.4. Removes dot segments from a URI path.
-///
-/// `std.fs.path.resolvePosix` is not sufficient here because it may return relative paths and does not preserve trailing slashes.
-fn removeDotSegments(allocator: Allocator, paths: []const []const u8) Allocator.Error![]const u8 {
-    var result = std.ArrayList(u8).init(allocator);
-    defer result.deinit();
-
-    for (paths) |p| {
-        var it = std.mem.tokenizeScalar(u8, p, '/');
-        while (it.next()) |component| {
-            if (std.mem.eql(u8, component, ".")) {
-                continue;
-            } else if (std.mem.eql(u8, component, "..")) {
-                if (result.items.len == 0)
-                    continue;
-
-                while (true) {
-                    const ends_with_slash = result.items[result.items.len - 1] == '/';
-                    result.items.len -= 1;
-                    if (ends_with_slash or result.items.len == 0) break;
-                }
-            } else {
-                try result.ensureUnusedCapacity(1 + component.len);
-                result.appendAssumeCapacity('/');
-                result.appendSliceAssumeCapacity(component);
-            }
-        }
-    }
-
-    // ensure a trailing slash is kept
-    const last_path = paths[paths.len - 1];
-    if (last_path.len > 0 and last_path[last_path.len - 1] == '/') {
-        try result.append('/');
-    }
-
-    return result.toOwnedSlice();
-}
+pub const ResolveInplaceError = ParseError || error{OutOfMemory};
 
 /// Resolves a URI against a base URI, conforming to RFC 3986, Section 5.
-///
-/// Assumes `arena` owns all memory in `base` and `ref`. `arena` will own all memory in the returned URI.
-pub fn resolve(base: Uri, ref: Uri, strict: bool, arena: Allocator) Allocator.Error!Uri {
-    var target: Uri = Uri{
-        .scheme = "",
-        .user = null,
-        .password = null,
-        .host = null,
-        .port = null,
-        .path = "",
-        .query = null,
-        .fragment = null,
+/// Copies `new` to the beginning of `aux_buf`, allowing the slices to overlap,
+/// then parses `new` as a URI, and then resolves the path in place.
+/// If a merge needs to take place, the newly constructed path will be stored
+/// in `aux_buf` just after the copied `new`.
+pub fn resolve_inplace(base: Uri, new: []const u8, aux_buf: []u8) ResolveInplaceError!Uri {
+    std.mem.copyBackwards(u8, aux_buf, new);
+    // At this point, new is an invalid pointer.
+    const new_mut = aux_buf[0..new.len];
+
+    const new_parsed, const has_scheme = p: {
+        break :p .{
+            parse(new_mut) catch |first_err| {
+                break :p .{
+                    parseWithoutScheme(new_mut) catch return first_err,
+                    false,
+                };
+            },
+            true,
+        };
     };
 
-    if (ref.scheme.len > 0 and (strict or !std.mem.eql(u8, ref.scheme, base.scheme))) {
-        target.scheme = ref.scheme;
-        target.user = ref.user;
-        target.host = ref.host;
-        target.port = ref.port;
-        target.path = try removeDotSegments(arena, &.{ref.path});
-        target.query = ref.query;
-    } else {
-        target.scheme = base.scheme;
-        if (ref.host) |host| {
-            target.user = ref.user;
-            target.host = host;
-            target.port = ref.port;
-            target.path = ref.path;
-            target.path = try removeDotSegments(arena, &.{ref.path});
-            target.query = ref.query;
-        } else {
-            if (ref.path.len == 0) {
-                target.path = base.path;
-                target.query = ref.query orelse base.query;
-            } else {
-                if (ref.path[0] == '/') {
-                    target.path = try removeDotSegments(arena, &.{ref.path});
-                } else {
-                    target.path = try removeDotSegments(arena, &.{ std.fs.path.dirnamePosix(base.path) orelse "", ref.path });
-                }
-                target.query = ref.query;
-            }
+    // As you can see above, `new_mut` is not a const pointer.
+    const new_path: []u8 = @constCast(new_parsed.path);
 
-            target.user = base.user;
-            target.host = base.host;
-            target.port = base.port;
-        }
-    }
+    if (has_scheme) return .{
+        .scheme = new_parsed.scheme,
+        .user = new_parsed.user,
+        .host = new_parsed.host,
+        .port = new_parsed.port,
+        .path = remove_dot_segments(new_path),
+        .query = new_parsed.query,
+        .fragment = new_parsed.fragment,
+    };
 
-    target.fragment = ref.fragment;
+    if (new_parsed.host) |host| return .{
+        .scheme = base.scheme,
+        .user = new_parsed.user,
+        .host = host,
+        .port = new_parsed.port,
+        .path = remove_dot_segments(new_path),
+        .query = new_parsed.query,
+        .fragment = new_parsed.fragment,
+    };
 
-    return target;
+    const path, const query = b: {
+        if (new_path.len == 0)
+            break :b .{
+                base.path,
+                new_parsed.query orelse base.query,
+            };
+
+        if (new_path[0] == '/')
+            break :b .{
+                remove_dot_segments(new_path),
+                new_parsed.query,
+            };
+
+        break :b .{
+            try merge_paths(base.path, new_path, aux_buf[new_mut.len..]),
+            new_parsed.query,
+        };
+    };
+
+    return .{
+        .scheme = base.scheme,
+        .user = base.user,
+        .host = base.host,
+        .port = base.port,
+        .path = path,
+        .query = query,
+        .fragment = new_parsed.fragment,
+    };
 }
 
-test resolve {
-    const base = try parse("http://a/b/c/d;p?q");
+/// In-place implementation of RFC 3986, Section 5.2.4.
+fn remove_dot_segments(path: []u8) []u8 {
+    var in_i: usize = 0;
+    var out_i: usize = 0;
+    while (in_i < path.len) {
+        if (std.mem.startsWith(u8, path[in_i..], "./")) {
+            in_i += 2;
+        } else if (std.mem.startsWith(u8, path[in_i..], "../")) {
+            in_i += 3;
+        } else if (std.mem.startsWith(u8, path[in_i..], "/./")) {
+            in_i += 2;
+        } else if (std.mem.eql(u8, path[in_i..], "/.")) {
+            in_i += 1;
+            path[in_i] = '/';
+        } else if (std.mem.startsWith(u8, path[in_i..], "/../")) {
+            in_i += 3;
+            while (out_i > 0) {
+                out_i -= 1;
+                if (path[out_i] == '/') break;
+            }
+        } else if (std.mem.eql(u8, path[in_i..], "/..")) {
+            in_i += 2;
+            path[in_i] = '/';
+            while (out_i > 0) {
+                out_i -= 1;
+                if (path[out_i] == '/') break;
+            }
+        } else if (std.mem.eql(u8, path[in_i..], ".")) {
+            in_i += 1;
+        } else if (std.mem.eql(u8, path[in_i..], "..")) {
+            in_i += 2;
+        } else {
+            while (true) {
+                path[out_i] = path[in_i];
+                out_i += 1;
+                in_i += 1;
+                if (in_i >= path.len or path[in_i] == '/') break;
+            }
+        }
+    }
+    return path[0..out_i];
+}
 
-    var arena = std.heap.ArenaAllocator.init(std.testing.allocator);
-    defer arena.deinit();
+test remove_dot_segments {
+    {
+        var buffer = "/a/b/c/./../../g".*;
+        try std.testing.expectEqualStrings("/a/g", remove_dot_segments(&buffer));
+    }
+}
 
-    try std.testing.expectEqualDeep(try parse("http://a/b/c/blog/"), try base.resolve(try parseWithoutScheme("blog/"), true, arena.allocator()));
-    try std.testing.expectEqualDeep(try parse("http://a/b/c/blog/?k"), try base.resolve(try parseWithoutScheme("blog/?k"), true, arena.allocator()));
-    try std.testing.expectEqualDeep(try parse("http://a/b/blog/"), try base.resolve(try parseWithoutScheme("../blog/"), true, arena.allocator()));
-    try std.testing.expectEqualDeep(try parse("http://a/b/blog"), try base.resolve(try parseWithoutScheme("../blog"), true, arena.allocator()));
-    try std.testing.expectEqualDeep(try parse("http://e"), try base.resolve(try parseWithoutScheme("//e"), true, arena.allocator()));
-    try std.testing.expectEqualDeep(try parse("https://a:1/"), try base.resolve(try parse("https://a:1/"), true, arena.allocator()));
+/// 5.2.3. Merge Paths
+fn merge_paths(base: []const u8, new: []u8, aux: []u8) error{OutOfMemory}![]u8 {
+    if (aux.len < base.len + 1 + new.len) return error.OutOfMemory;
+    if (base.len == 0) {
+        aux[0] = '/';
+        @memcpy(aux[1..][0..new.len], new);
+        return remove_dot_segments(aux[0 .. new.len + 1]);
+    }
+    const pos = std.mem.lastIndexOfScalar(u8, base, '/') orelse return remove_dot_segments(new);
+    @memcpy(aux[0 .. pos + 1], base[0 .. pos + 1]);
+    @memcpy(aux[pos + 1 ..][0..new.len], new);
+    return remove_dot_segments(aux[0 .. pos + 1 + new.len]);
 }
 
 const SliceReader = struct {
diff --git a/lib/std/http/Client.zig b/lib/std/http/Client.zig
index 3b563d6f71..03ec7610f7 100644
--- a/lib/std/http/Client.zig
+++ b/lib/std/http/Client.zig
@@ -597,9 +597,6 @@ pub const Request = struct {
     /// This field is undefined until `wait` is called.
     response: Response,
 
-    /// Used as a allocator for resolving redirects locations.
-    arena: std.heap.ArenaAllocator,
-
     /// Standard headers that have default, but overridable, behavior.
     headers: Headers,
 
@@ -661,8 +658,6 @@ pub const Request = struct {
             }
             req.client.connection_pool.release(req.client.allocator, connection);
         }
-
-        req.arena.deinit();
         req.* = undefined;
     }
 
@@ -842,11 +837,12 @@ pub const Request = struct {
     }
 
     pub const WaitError = RequestError || SendError || TransferReadError ||
-        proto.HeadersParser.CheckCompleteHeadError || Response.ParseError || Uri.ParseError ||
+        proto.HeadersParser.CheckCompleteHeadError || Response.ParseError ||
         error{ // TODO: file zig fmt issue for this bad indentation
         TooManyHttpRedirects,
         RedirectRequiresResend,
-        HttpRedirectMissingLocation,
+        HttpRedirectLocationMissing,
+        HttpRedirectLocationInvalid,
         CompressionInitializationFailed,
         CompressionUnsupported,
     };
@@ -927,31 +923,40 @@ pub const Request = struct {
             }
 
             if (req.response.status.class() == .redirect and req.redirect_behavior != .unhandled) {
-                req.response.skip = true;
-
                 // skip the body of the redirect response, this will at least
                 // leave the connection in a known good state.
+                req.response.skip = true;
                 assert(try req.transferRead(&.{}) == 0); // we're skipping, no buffer is necessary
 
                 if (req.redirect_behavior == .not_allowed) return error.TooManyHttpRedirects;
 
                 const location = req.response.location orelse
-                    return error.HttpRedirectMissingLocation;
+                    return error.HttpRedirectLocationMissing;
 
-                const arena = req.arena.allocator();
+                // This mutates the beginning of header_buffer and uses that
+                // for the backing memory of the returned new_uri.
+                const header_buffer = req.response.parser.header_bytes_buffer;
+                const new_uri = req.uri.resolve_inplace(location, header_buffer) catch
+                    return error.HttpRedirectLocationInvalid;
 
-                const location_duped = try arena.dupe(u8, location);
-
-                const new_url = Uri.parse(location_duped) catch try Uri.parseWithoutScheme(location_duped);
-                const resolved_url = try req.uri.resolve(new_url, false, arena);
+                // The new URI references the beginning of header_bytes_buffer memory.
+                // That memory will be kept, but everything after it will be
+                // reused by the subsequent request. In other words,
+                // header_bytes_buffer must be large enough to store all
+                // redirect locations as well as the final request header.
+                const path_end = new_uri.path.ptr + new_uri.path.len;
+                // https://github.com/ziglang/zig/issues/1738
+                const path_offset = @intFromPtr(path_end) - @intFromPtr(header_buffer.ptr);
+                const end_offset = @max(path_offset, location.len);
+                req.response.parser.header_bytes_buffer = header_buffer[end_offset..];
 
                 const is_same_domain_or_subdomain =
-                    std.ascii.endsWithIgnoreCase(resolved_url.host.?, req.uri.host.?) and
-                    (resolved_url.host.?.len == req.uri.host.?.len or
-                    resolved_url.host.?[resolved_url.host.?.len - req.uri.host.?.len - 1] == '.');
+                    std.ascii.endsWithIgnoreCase(new_uri.host.?, req.uri.host.?) and
+                    (new_uri.host.?.len == req.uri.host.?.len or
+                    new_uri.host.?[new_uri.host.?.len - req.uri.host.?.len - 1] == '.');
 
-                if (resolved_url.host == null or !is_same_domain_or_subdomain or
-                    !std.ascii.eqlIgnoreCase(resolved_url.scheme, req.uri.scheme))
+                if (new_uri.host == null or !is_same_domain_or_subdomain or
+                    !std.ascii.eqlIgnoreCase(new_uri.scheme, req.uri.scheme))
                 {
                     // When redirecting to a different domain, strip privileged headers.
                     req.privileged_headers = &.{};
@@ -975,7 +980,7 @@ pub const Request = struct {
                     return error.RedirectRequiresResend;
                 }
 
-                try req.redirect(resolved_url);
+                try req.redirect(new_uri);
                 try req.send(.{});
             } else {
                 req.response.skip = false;
@@ -1341,7 +1346,7 @@ pub fn connectTunnel(
             client.connection_pool.release(client.allocator, conn);
         }
 
-        const uri = Uri{
+        const uri: Uri = .{
             .scheme = "http",
             .user = null,
             .password = null,
@@ -1548,15 +1553,12 @@ pub fn open(
             .version = undefined,
             .parser = proto.HeadersParser.init(options.server_header_buffer),
         },
-        .arena = undefined,
         .headers = options.headers,
         .extra_headers = options.extra_headers,
         .privileged_headers = options.privileged_headers,
     };
     errdefer req.deinit();
 
-    req.arena = std.heap.ArenaAllocator.init(client.allocator);
-
     return req;
 }