diff --git a/MdePkg/Include/Library/BaseLib.h b/MdePkg/Include/Library/BaseLib.h
index 1eb842384e..c58e4b089d 100644
--- a/MdePkg/Include/Library/BaseLib.h
+++ b/MdePkg/Include/Library/BaseLib.h
@@ -2,7 +2,7 @@
   Provides string functions, linked list functions, math functions, synchronization
   functions, file path functions, and CPU architecture-specific functions.
 
-Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2006 - 2019, Intel Corporation. All rights reserved.<BR>
 Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
 This program and the accompanying materials
 are licensed and made available under the terms and conditions of the BSD License
@@ -2720,6 +2720,46 @@ AsciiStrnToUnicodeStrS (
   OUT     UINTN                     *DestinationLength
   );
 
+/**
+  Convert a Unicode character to upper case only if
+  it maps to a valid small-case ASCII character.
+
+  This internal function only deal with Unicode character
+  which maps to a valid small-case ASCII character, i.e.
+  L'a' to L'z'. For other Unicode character, the input character
+  is returned directly.
+
+  @param  Char  The character to convert.
+
+  @retval LowerCharacter   If the Char is with range L'a' to L'z'.
+  @retval Unchanged        Otherwise.
+
+**/
+CHAR16
+EFIAPI
+CharToUpper (
+  IN      CHAR16                    Char
+  );
+
+/**
+  Converts a lowercase Ascii character to upper one.
+
+  If Chr is lowercase Ascii character, then converts it to upper one.
+
+  If Value >= 0xA0, then ASSERT().
+  If (Value & 0x0F) >= 0x0A, then ASSERT().
+
+  @param  Chr   one Ascii character
+
+  @return The uppercase value of Ascii character
+
+**/
+CHAR8
+EFIAPI
+AsciiCharToUpper (
+  IN      CHAR8                     Chr
+  );
+
 /**
   Converts an 8-bit value to an 8-bit BCD value.
 
diff --git a/MdePkg/Library/BaseLib/SafeString.c b/MdePkg/Library/BaseLib/SafeString.c
index 417497cbc9..27e337f0aa 100644
--- a/MdePkg/Library/BaseLib/SafeString.c
+++ b/MdePkg/Library/BaseLib/SafeString.c
@@ -1,7 +1,7 @@
 /** @file
   Safe String functions.
 
-  Copyright (c) 2014 - 2018, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2014 - 2019, Intel Corporation. All rights reserved.<BR>
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD License
   which accompanies this distribution.  The full text of the license may be found at
@@ -905,7 +905,7 @@ StrHexToUintnS (
     String++;
   }
 
-  if (InternalCharToUpper (*String) == L'X') {
+  if (CharToUpper (*String) == L'X') {
     if (*(String - 1) != L'0') {
       *Data = 0;
       return RETURN_SUCCESS;
@@ -1036,7 +1036,7 @@ StrHexToUint64S (
     String++;
   }
 
-  if (InternalCharToUpper (*String) == L'X') {
+  if (CharToUpper (*String) == L'X') {
     if (*(String - 1) != L'0') {
       *Data = 0;
       return RETURN_SUCCESS;
@@ -2459,7 +2459,7 @@ AsciiStrHexToUintnS (
     String++;
   }
 
-  if (InternalBaseLibAsciiToUpper (*String) == 'X') {
+  if (AsciiCharToUpper (*String) == 'X') {
     if (*(String - 1) != '0') {
       *Data = 0;
       return RETURN_SUCCESS;
@@ -2586,7 +2586,7 @@ AsciiStrHexToUint64S (
     String++;
   }
 
-  if (InternalBaseLibAsciiToUpper (*String) == 'X') {
+  if (AsciiCharToUpper (*String) == 'X') {
     if (*(String - 1) != '0') {
       *Data = 0;
       return RETURN_SUCCESS;
diff --git a/MdePkg/Library/BaseLib/String.c b/MdePkg/Library/BaseLib/String.c
index e6df12797d..467d91069d 100644
--- a/MdePkg/Library/BaseLib/String.c
+++ b/MdePkg/Library/BaseLib/String.c
@@ -1,7 +1,7 @@
 /** @file
   Unicode and ASCII string primitives.
 
-  Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2006 - 2019, Intel Corporation. All rights reserved.<BR>
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD License
   which accompanies this distribution.  The full text of the license may be found at
@@ -552,7 +552,7 @@ InternalIsDecimalDigitCharacter (
 **/
 CHAR16
 EFIAPI
-InternalCharToUpper (
+CharToUpper (
   IN      CHAR16                    Char
   )
 {
@@ -586,7 +586,7 @@ InternalHexCharToUintn (
     return Char - L'0';
   }
 
-  return (10 + InternalCharToUpper (Char) - L'A');
+  return (10 + CharToUpper (Char) - L'A');
 }
 
 /**
@@ -1181,7 +1181,7 @@ AsciiStrCmp (
 **/
 CHAR8
 EFIAPI
-InternalBaseLibAsciiToUpper (
+AsciiCharToUpper (
   IN      CHAR8                     Chr
   )
 {
@@ -1211,7 +1211,7 @@ InternalAsciiHexCharToUintn (
     return Char - '0';
   }
 
-  return (10 + InternalBaseLibAsciiToUpper (Char) - 'A');
+  return (10 + AsciiCharToUpper (Char) - 'A');
 }
 
 
@@ -1260,13 +1260,13 @@ AsciiStriCmp (
   ASSERT (AsciiStrSize (FirstString));
   ASSERT (AsciiStrSize (SecondString));
 
-  UpperFirstString  = InternalBaseLibAsciiToUpper (*FirstString);
-  UpperSecondString = InternalBaseLibAsciiToUpper (*SecondString);
+  UpperFirstString  = AsciiCharToUpper (*FirstString);
+  UpperSecondString = AsciiCharToUpper (*SecondString);
   while ((*FirstString != '\0') && (*SecondString != '\0') && (UpperFirstString == UpperSecondString)) {
     FirstString++;
     SecondString++;
-    UpperFirstString  = InternalBaseLibAsciiToUpper (*FirstString);
-    UpperSecondString = InternalBaseLibAsciiToUpper (*SecondString);
+    UpperFirstString  = AsciiCharToUpper (*FirstString);
+    UpperSecondString = AsciiCharToUpper (*SecondString);
   }
 
   return UpperFirstString - UpperSecondString;