diff --git a/build.zig b/build.zig
index 8611afabdef3..2c68e29b2472 100644
--- a/build.zig
+++ b/build.zig
@@ -609,6 +609,8 @@ pub fn build(b: *std.Build) !void {
         .optimize_modes = optimization_modes,
         .test_filters = test_filters,
         .test_target_filters = test_target_filters,
+        // Highest RSS observed in any test case was exactly 1465151488 on x86_64-linux CI.
+        .max_rss = 1758181785,
     })) |test_libc_step| test_step.dependOn(test_libc_step);
 }
 
diff --git a/ci/x86_64-linux-release.sh b/ci/x86_64-linux-release.sh
index 08144ff3f076..39120b25bf0b 100755
--- a/ci/x86_64-linux-release.sh
+++ b/ci/x86_64-linux-release.sh
@@ -62,6 +62,7 @@ stage3-release/bin/zig build \
 stage3-release/bin/zig build test docs \
   --maxrss 21000000000 \
   -Dlldb=$HOME/deps/lldb-zig/Release-e0a42bb34/bin/lldb \
+  -Dlibc-test-path=$HOME/deps/libc-test-f2bac77 \
   -fqemu \
   -fwasmtime \
   -Dstatic-llvm \
diff --git a/test/libc.zig b/test/libc.zig
index b11821534644..7b1953e2418f 100644
--- a/test/libc.zig
+++ b/test/libc.zig
@@ -91,7 +91,7 @@ pub fn addCases(cases: *tests.LibcContext) void {
     cases.addLibcTestCase("regression/lseek-large.c", false, .{});
     cases.addLibcTestCase("regression/malloc-0.c", true, .{});
     // "regression/malloc-brk-fail.c": QEMU OOM
-    cases.addLibcTestCase("regression/malloc-oom.c", false, .{}); // wasi-libc: requires t_memfill
+    // cases.addLibcTestCase("regression/malloc-oom.c", false, .{}); // wasi-libc: requires t_memfill; QEMU OOM
     cases.addLibcTestCase("regression/mbsrtowcs-overflow.c", true, .{});
     cases.addLibcTestCase("regression/memmem-oob-read.c", true, .{});
     cases.addLibcTestCase("regression/memmem-oob.c", true, .{});
diff --git a/test/src/Libc.zig b/test/src/Libc.zig
index 7a5801ea28b8..708e4c7bb800 100644
--- a/test/src/Libc.zig
+++ b/test/src/Libc.zig
@@ -10,6 +10,7 @@ pub const Options = struct {
     optimize_modes: []const std.builtin.OptimizeMode,
     test_filters: []const []const u8,
     test_target_filters: []const []const u8,
+    max_rss: usize,
 };
 
 const TestCase = struct {
@@ -100,6 +101,7 @@ pub fn addTarget(libc: *const Libc, target: std.Build.ResolvedTarget) void {
             const exe = libc.b.addExecutable(.{
                 .name = test_case.name,
                 .root_module = mod,
+                .max_rss = libc.options.max_rss,
             });
 
             const run = libc.b.addRunArtifact(exe);
@@ -108,6 +110,7 @@ pub fn addTarget(libc: *const Libc, target: std.Build.ResolvedTarget) void {
             run.expectStdErrEqual("");
             run.expectStdOutEqual("");
             run.expectExitCode(0);
+            run.step.max_rss = libc.options.max_rss;
 
             libc.root_step.dependOn(&run.step);
         }