diff --git a/CMakeLists.txt b/CMakeLists.txt
index e50d49c81e16..e5881bbdf97d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -108,7 +108,7 @@ endif()
 
 # The minimum compiler versions should match those listed in both
 # doc/developers.rst and tools/workspace/cc/repository.bzl.
-set(MINIMUM_APPLE_CLANG_VERSION 11)
+set(MINIMUM_APPLE_CLANG_VERSION 12)
 set(MINIMUM_CLANG_VERSION 9)
 set(MINIMUM_GNU_VERSION 7.5)
 
diff --git a/doc/developers.rst b/doc/developers.rst
index 52f5b192c089..c57d88e2e036 100644
--- a/doc/developers.rst
+++ b/doc/developers.rst
@@ -85,8 +85,8 @@ Drake requires a compiler running in C++17 mode.
 | Ubuntu 20.04 LTS (Focal Fossa)   |       | 3.16  | | GCC 9.3 (default) |                   | 3.8    |
 |                                  |       |       | | Clang 9           |                   |        |
 +----------------------------------+       +-------+---------------------+-------------------+        |
-| macOS Catalina (10.15)           |       | 3.18  | | Apple LLVM 12.0.0 | | AdoptOpenJDK 15 |        |
-|                                  |       |       | | (Xcode 12.2)      | | (HotSpot JVM)   |        |
+| macOS Catalina (10.15)           |       | 3.19  | | Apple LLVM 12.0.0 | | AdoptOpenJDK 15 |        |
+|                                  |       |       | | (Xcode 12.4)      | | (HotSpot JVM)   |        |
 +----------------------------------+-------+-------+---------------------+-------------------+--------+
 
 CPython is the only Python implementation supported. On Ubuntu, amd64
diff --git a/tools/macos.bazelrc b/tools/macos.bazelrc
index af3797f7be0b..92cdea11409b 100644
--- a/tools/macos.bazelrc
+++ b/tools/macos.bazelrc
@@ -2,11 +2,6 @@
 # N.B. Ensure this is consistent with `execute.bzl`.
 build --action_env=PATH=/usr/local/bin:/usr/bin:/bin
 
-# Work around alignment-related issues when compiling code that uses
-# Eigen <= 3.3.7 with Apple LLVM 11.0.0. Most are fixed in the 3.3 branch of
-# Eigen as of commit a5c3d12.
-build --copt=-fno-stack-check
-
 # Suppress numerous "'_FORTIFY_SOURCE' macro redefined" warnings when using
 # sanitizers.
 build:asan --copt=-Wno-macro-redefined
diff --git a/tools/workspace/cc/repository.bzl b/tools/workspace/cc/repository.bzl
index 0324608ac1cd..3a4955569328 100644
--- a/tools/workspace/cc/repository.bzl
+++ b/tools/workspace/cc/repository.bzl
@@ -120,8 +120,8 @@ def _impl(repository_ctx):
     # even if they happen to support the necessary compiler flags.
 
     if compiler_id == "AppleClang":
-        if compiler_version_major < 11:
-            fail("AppleClang compiler version {}.{} is less than 11.0.".format(
+        if compiler_version_major < 12:
+            fail("AppleClang compiler version {}.{} is less than 12.0.".format(
                 compiler_version_major,
                 compiler_version_minor,
             ))
diff --git a/tools/workspace/os.bzl b/tools/workspace/os.bzl
index d33b972419e6..27801b9d54f1 100644
--- a/tools/workspace/os.bzl
+++ b/tools/workspace/os.bzl
@@ -106,13 +106,16 @@ def _determine_macos(repository_ctx):
         return _make_result(error = error_prologue + sw_vers.error)
 
     major_minor_versions = sw_vers.stdout.strip().split(".")[:2]
-    macos_release = ".".join(major_minor_versions)
+    if int(major_minor_versions[0]) < 11:
+        macos_release = ".".join(major_minor_versions)
+    else:
+        macos_release = major_minor_versions[0]
 
     # Match supported macOS release(s).
-    if macos_release in ["10.15", "11.0"]:
-        if macos_release == "11.0":
+    if macos_release in ["10.15", "11"]:
+        if macos_release == "11":
             print(
-                "WARNING: macOS Big Sur 11.0 is NOT yet supported. " +
+                "WARNING: macOS Big Sur 11.x is NOT yet supported. " +
                 "Compilation, tests, and/or other functionality may fail.",
             )
         return _make_result(macos_release = macos_release)
@@ -135,7 +138,8 @@ def determine_os(repository_ctx):
         - error: str iff any error occurred, else None
         - distribution: str either "ubuntu" or "macos" if no error
         - is_macos: True iff on a supported macOS release, else False
-        - macos_release: str like "10.15" iff on a supported macOS, else None
+        - macos_release: str like "10.15" or "11" iff on a supported macOS,
+                         else None
         - is_ubuntu: True iff on a supported Ubuntu version, else False
         - ubuntu_release: str like "18.04" iff on a supported ubuntu, else None
     """