diff --git a/icu4c/source/common/uloc_tag.cpp b/icu4c/source/common/uloc_tag.cpp
index b4e3c92..7f7fd91 100644
--- a/icu4c/source/common/uloc_tag.cpp
+++ b/icu4c/source/common/uloc_tag.cpp
@@ -1988,11 +1988,12 @@
 #define PRIV 0x0080
 
 /**
- * Ticket #12705 - Visual Studio 2015 Update 3 contains a new code optimizer which has problems optimizing
- * this function. (See https://blogs.msdn.microsoft.com/vcblog/2016/05/04/new-code-optimizer/ )
- * As a workaround, we will turn off optimization just for this function on VS2015 Update 3 and above.
+ * Ticket #12705 - The optimizer in Visual Studio 2015 Update 3 has problems optimizing this function.
+ * As a work-around, optimization is disabled for this function on VS2015 and VS2017.
+ * This work-around should be removed once the following versions of Visual Studio are no
+ * longer supported: All versions of VS2015/VS2017, and versions of VS2019 below 16.4.
  */
-#if (defined(_MSC_VER) && (_MSC_VER >= 1900) && defined(_MSC_FULL_VER) && (_MSC_FULL_VER >= 190024210))
+#if defined(_MSC_VER) && (_MSC_VER >= 1900) && (_MSC_VER < 1924)
 #pragma optimize( "", off )
 #endif
 
@@ -2405,10 +2406,8 @@
     return t.orphan();
 }
 
-/**
-* Ticket #12705 - Turn optimization back on.
-*/
-#if (defined(_MSC_VER) && (_MSC_VER >= 1900) && defined(_MSC_FULL_VER) && (_MSC_FULL_VER >= 190024210))
+// Ticket #12705 - Turn optimization back on.
+#if defined(_MSC_VER) && (_MSC_VER >= 1900) && (_MSC_VER < 1924)
 #pragma optimize( "", on )
 #endif
 
diff --git a/icu4c/source/test/cintltst/utf8tst.c b/icu4c/source/test/cintltst/utf8tst.c
index 4884be4..de36615 100644
--- a/icu4c/source/test/cintltst/utf8tst.c
+++ b/icu4c/source/test/cintltst/utf8tst.c
@@ -758,10 +758,12 @@
 }
 
 /**
-* Ticket #13636 - Visual Studio 2017 has problems optimizing this function.
-* As a workaround, we will turn off optimization just for this function on VS2017 and above.
-*/
-#if defined(_MSC_VER) && (_MSC_VER > 1900)
+ * Ticket #13636 - The optimizer in Visual Studio 2017 has problems optimizing this function.
+ * As a work-around, optimization is disabled for this function on VS2017.
+ * This work-around should be removed once the following versions of Visual Studio are no
+ * longer supported: All versions of VS2017, and versions of VS2019 below 16.4.
+ */
+#if defined(_MSC_VER) && (_MSC_VER > 1900) && (_MSC_VER < 1924)
 #pragma optimize( "", off )
 #endif
 
@@ -850,10 +852,8 @@
     }
 }
 
-/**
-* Ticket #13636 - Turn optimization back on.
-*/
-#if defined(_MSC_VER) && (_MSC_VER > 1900)
+// Ticket #13636 - Turn optimization back on.
+#if defined(_MSC_VER) && (_MSC_VER > 1900) && (_MSC_VER < 1924)
 #pragma optimize( "", on )
 #endif