diff --git a/site/source/docs/tools_reference/settings_reference.rst b/site/source/docs/tools_reference/settings_reference.rst
index d8e7116976217..07dcd98a20c14 100644
--- a/site/source/docs/tools_reference/settings_reference.rst
+++ b/site/source/docs/tools_reference/settings_reference.rst
@@ -2860,7 +2860,7 @@ are desired to work. Pass -sMIN_FIREFOX_VERSION=majorVersion to drop support
 for Firefox versions older than < majorVersion.
 Firefox 79 was released on 2020-07-28.
 MAX_INT (0x7FFFFFFF, or -1) specifies that target is not supported.
-Minimum supported value is 50 which was released on 2016-11-15 (see
+Minimum supported value is 55 which was released on 2017-08-08 (see
 feature_matrix.py)
 
 Default value: 79
@@ -2879,8 +2879,10 @@ bundled with macOS 10.14.0 Mojave.
 NOTE: Emscripten is unable to produce code that would work in iOS 9.3.5 and
 older, i.e. iPhone 4s, iPad 2, iPad 3, iPad Mini 1, Pod Touch 5 and older,
 see https://github.com/emscripten-core/emscripten/pull/7191.
+Multithreaded Emscripten code will need Safari 12.2 (iPhone 5s+) at minimum,
+with support for DedicatedWorkerGlobalScope.name parameter.
 MAX_INT (0x7FFFFFFF, or -1) specifies that target is not supported.
-Minimum supported value is 101000 which was released in 2016-09 (see
+Minimum supported value is 120200 which was released on 2019-03-25 (see
 feature_matrix.py).
 
 Default value: 150000
@@ -2896,7 +2898,7 @@ This setting also applies to modern Chromium-based Edge, which shares version
 numbers with Chrome.
 Chrome 85 was released on 2020-08-25.
 MAX_INT (0x7FFFFFFF, or -1) specifies that target is not supported.
-Minimum supported value is 55, which was released on 2016-12-01 (see
+Minimum supported value is 70, which was released on 2018-10-16 (see
 feature_matrix.py).
 
 Default value: 85
diff --git a/src/settings.js b/src/settings.js
index c5d63adf9414e..cb4790945bb25 100644
--- a/src/settings.js
+++ b/src/settings.js
@@ -1870,7 +1870,7 @@ var AUTO_NATIVE_LIBRARIES = true;
 // for Firefox versions older than < majorVersion.
 // Firefox 79 was released on 2020-07-28.
 // MAX_INT (0x7FFFFFFF, or -1) specifies that target is not supported.
-// Minimum supported value is 50 which was released on 2016-11-15 (see
+// Minimum supported value is 55 which was released on 2017-08-08 (see
 // feature_matrix.py)
 // [link]
 var MIN_FIREFOX_VERSION = 79;
@@ -1884,8 +1884,10 @@ var MIN_FIREFOX_VERSION = 79;
 // NOTE: Emscripten is unable to produce code that would work in iOS 9.3.5 and
 // older, i.e. iPhone 4s, iPad 2, iPad 3, iPad Mini 1, Pod Touch 5 and older,
 // see https://github.com/emscripten-core/emscripten/pull/7191.
+// Multithreaded Emscripten code will need Safari 12.2 (iPhone 5s+) at minimum,
+// with support for DedicatedWorkerGlobalScope.name parameter.
 // MAX_INT (0x7FFFFFFF, or -1) specifies that target is not supported.
-// Minimum supported value is 101000 which was released in 2016-09 (see
+// Minimum supported value is 120200 which was released on 2019-03-25 (see
 // feature_matrix.py).
 // [link]
 var MIN_SAFARI_VERSION = 150000;
@@ -1896,7 +1898,7 @@ var MIN_SAFARI_VERSION = 150000;
 // numbers with Chrome.
 // Chrome 85 was released on 2020-08-25.
 // MAX_INT (0x7FFFFFFF, or -1) specifies that target is not supported.
-// Minimum supported value is 55, which was released on 2016-12-01 (see
+// Minimum supported value is 70, which was released on 2018-10-16 (see
 // feature_matrix.py).
 // [link]
 var MIN_CHROME_VERSION = 85;
diff --git a/test/test_other.py b/test/test_other.py
index 7cba06185531c..5d45d8f312ebd 100644
--- a/test/test_other.py
+++ b/test/test_other.py
@@ -15226,8 +15226,8 @@ def test_reproduce(self):
     self.assertTextDataIdentical(expected, response)
 
   def test_min_browser_version(self):
-    err = self.expect_fail([EMCC, test_file('hello_world.c'), '-Wno-transpile', '-Werror', '-sWASM_BIGINT', '-sMIN_SAFARI_VERSION=120000'])
-    self.assertContained('emcc: error: MIN_SAFARI_VERSION=120000 is not compatible with WASM_BIGINT (150000 or above required)', err)
+    err = self.expect_fail([EMCC, test_file('hello_world.c'), '-Wno-transpile', '-Werror', '-sWASM_BIGINT', '-sMIN_SAFARI_VERSION=130000'])
+    self.assertContained('emcc: error: MIN_SAFARI_VERSION=130000 is not compatible with WASM_BIGINT (150000 or above required)', err)
 
     err = self.expect_fail([EMCC, test_file('hello_world.c'), '-Wno-transpile', '-Werror', '-pthread', '-sMIN_CHROME_VERSION=73'])
     self.assertContained('emcc: error: MIN_CHROME_VERSION=73 is not compatible with pthreads (74 or above required)', err)
@@ -15241,7 +15241,7 @@ def test_signext_lowering(self):
     self.assertNotContained('--signext-lowering', err)
 
     # Specifying an older browser version should trigger the lowering pass
-    err = self.run_process(cmd + ['-sMIN_SAFARI_VERSION=120000'], stderr=subprocess.PIPE).stderr
+    err = self.run_process(cmd + ['-sMIN_SAFARI_VERSION=120200'], stderr=subprocess.PIPE).stderr
     self.assertContained('--signext-lowering', err)
     err = self.run_process(cmd + ['-sMIN_FIREFOX_VERSION=61'], stderr=subprocess.PIPE).stderr
     self.assertContained('--signext-lowering', err)
@@ -15991,7 +15991,7 @@ def test_no_extra_output(self):
 
   def test_browser_too_old(self):
     err = self.expect_fail([EMCC, test_file('hello_world.c'), '-sMIN_CHROME_VERSION=10'])
-    self.assertContained('emcc: error: MIN_CHROME_VERSION older than 55 is not supported', err)
+    self.assertContained('emcc: error: MIN_CHROME_VERSION older than 70 is not supported', err)
 
   def test_js_only_settings(self):
     err = self.run_process([EMCC, test_file('hello_world.c'), '-o', 'foo.wasm', '-sDEFAULT_LIBRARY_FUNCS_TO_INCLUDE=emscripten_get_heap_max'], stderr=PIPE).stderr
diff --git a/tools/feature_matrix.py b/tools/feature_matrix.py
index dfd3dbb295c11..03fb0c92f45eb 100644
--- a/tools/feature_matrix.py
+++ b/tools/feature_matrix.py
@@ -15,12 +15,16 @@
 
 UNSUPPORTED = 0x7FFFFFFF
 
-# Oldest support browser versions.  These have been set somewhat
-# arbitrarily for now.
-# TODO(sbc): Design a of policy for managing these values.
-OLDEST_SUPPORTED_CHROME = 55  # December 1, 2016
-OLDEST_SUPPORTED_FIREFOX = 50  # November 15, 2016
-OLDEST_SUPPORTED_SAFARI = 101000  # September 20, 2016
+# Oldest support browser versions.
+# Emscripten unconditionally requires support for:
+# - DedicatedWorkerGlobalScope.name parameter for multithreading support, which
+#   landed first in Chrome 70, Firefox 55 and Safari 12.2.
+
+# N.b. when modifying these values, update comments in src/settings.js on
+# MIN_x_VERSION fields to match accordingly.
+OLDEST_SUPPORTED_CHROME = 70  # Released on 2018-10-16
+OLDEST_SUPPORTED_FIREFOX = 55  # Released on 2017-08-08
+OLDEST_SUPPORTED_SAFARI = 120200  # Released on 2019-03-25
 # 10.19.0 is the oldest version of node that we do any testing with.
 # Keep this in sync with the test-node-compat in .circleci/config.yml.
 OLDEST_SUPPORTED_NODE = 101900