diff --git a/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.h b/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.h
--- a/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.h
+++ b/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.h
@@ -69,8 +69,8 @@
   struct NamingStyle {
     NamingStyle() = default;
 
-    NamingStyle(llvm::Optional<CaseType> Case, const std::string &Prefix,
-                const std::string &Suffix, const std::string &IgnoredRegexpStr,
+    NamingStyle(llvm::Optional<CaseType> Case, StringRef Prefix,
+                StringRef Suffix, StringRef IgnoredRegexpStr,
                 HungarianPrefixType HPType);
     NamingStyle(const NamingStyle &O) = delete;
     NamingStyle &operator=(NamingStyle &&O) = default;
diff --git a/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp b/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp
--- a/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp
@@ -228,9 +228,8 @@
 // clang-format on
 
 IdentifierNamingCheck::NamingStyle::NamingStyle(
-    llvm::Optional<IdentifierNamingCheck::CaseType> Case,
-    const std::string &Prefix, const std::string &Suffix,
-    const std::string &IgnoredRegexpStr, HungarianPrefixType HPType)
+    llvm::Optional<IdentifierNamingCheck::CaseType> Case, StringRef Prefix,
+    StringRef Suffix, StringRef IgnoredRegexpStr, HungarianPrefixType HPType)
     : Case(Case), Prefix(Prefix), Suffix(Suffix),
       IgnoredRegexpStr(IgnoredRegexpStr), HPType(HPType) {
   if (!IgnoredRegexpStr.empty()) {
@@ -263,22 +262,21 @@
 
     memcpy(&StyleString[StyleSize], "IgnoredRegexp", 13);
     StyleString.truncate(StyleSize + 13);
-    StringRef IgnoredRegexpStr = Options.get(StyleString, "");
+    Optional<StringRef> IgnoredRegexpStr = Options.get(StyleString);
     memcpy(&StyleString[StyleSize], "Prefix", 6);
     StyleString.truncate(StyleSize + 6);
-    std::string Prefix(Options.get(StyleString, ""));
+    Optional<StringRef> Prefix(Options.get(StyleString));
     // Fast replacement of [Pre]fix -> [Suf]fix.
     memcpy(&StyleString[StyleSize], "Suf", 3);
-    std::string Postfix(Options.get(StyleString, ""));
+    Optional<StringRef> Postfix(Options.get(StyleString));
     memcpy(&StyleString[StyleSize], "Case", 4);
     StyleString.pop_back_n(2);
-    auto CaseOptional =
+    Optional<CaseType> CaseOptional =
         Options.get<IdentifierNamingCheck::CaseType>(StyleString);
 
-    if (CaseOptional || !Prefix.empty() || !Postfix.empty() ||
-        !IgnoredRegexpStr.empty() || HPTOpt)
-      Styles[I].emplace(std::move(CaseOptional), std::move(Prefix),
-                        std::move(Postfix), IgnoredRegexpStr.str(),
+    if (CaseOptional || Prefix || Postfix || IgnoredRegexpStr || HPTOpt)
+      Styles[I].emplace(std::move(CaseOptional), Prefix.getValueOr(""),
+                        Postfix.getValueOr(""), IgnoredRegexpStr.getValueOr(""),
                         HPTOpt.value_or(IdentifierNamingCheck::HPT_Off));
   }
   bool IgnoreMainLike = Options.get("IgnoreMainLikeFunctions", false);
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -234,6 +234,11 @@
 - Fixed incorrect suggestions for :doc:`readability-container-size-empty
   <clang-tidy/checks/readability/container-size-empty>` when smart pointers are involved.
 
+- Fixed an issue in :doc:`readability-identifier-naming
+  <clang-tidy/checks/readability/identifier-naming>` when specifying an empty
+  string for ``Prefix`` or ``Suffix`` options could result in the style not
+  being used.
+
 - Fixed a false positive in :doc:`readability-non-const-parameter
   <clang-tidy/checks/readability/non-const-parameter>` when the parameter is
   referenced by an lvalue.
diff --git a/clang-tools-extra/test/clang-tidy/checkers/readability/identifier-naming-empty-options.cpp b/clang-tools-extra/test/clang-tidy/checkers/readability/identifier-naming-empty-options.cpp
new file mode 100644
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/readability/identifier-naming-empty-options.cpp
@@ -0,0 +1,12 @@
+// RUN: %check_clang_tidy %s readability-identifier-naming %t -- \
+// RUN:   -config='{CheckOptions: { \
+// RUN:     readability-identifier-naming.GlobalConstantPrefix: "", \
+// RUN:     readability-identifier-naming.GlobalVariablePrefix: g_ }}'
+
+int BadGlobalVariable;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: invalid case style for global variable 'BadGlobalVariable' [readability-identifier-naming]
+// CHECK-FIXES: int g_BadGlobalVariable;
+int g_GoodGlobalVariable;
+
+const int GoodGlobalConstant = 0;
+const int g_IgnoreGlobalConstant = 0;