diff --git a/clang-tools-extra/clang-tidy/llvmlibc/InlineFunctionDeclCheck.cpp b/clang-tools-extra/clang-tidy/llvmlibc/InlineFunctionDeclCheck.cpp
--- a/clang-tools-extra/clang-tidy/llvmlibc/InlineFunctionDeclCheck.cpp
+++ b/clang-tools-extra/clang-tidy/llvmlibc/InlineFunctionDeclCheck.cpp
@@ -88,7 +88,7 @@
 
   diag(SrcBegin, "%0 must be tagged with the LIBC_INLINE macro; the macro "
                  "should be placed at the beginning of the declaration")
-      << FuncDecl;
+      << FuncDecl << FixItHint::CreateInsertion(Loc, "LIBC_INLINE ");
 }
 
 } // namespace clang::tidy::llvm_libc
diff --git a/clang-tools-extra/test/clang-tidy/checkers/llvmlibc/inline-function-decl.hpp b/clang-tools-extra/test/clang-tidy/checkers/llvmlibc/inline-function-decl.hpp
--- a/clang-tools-extra/test/clang-tidy/checkers/llvmlibc/inline-function-decl.hpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/llvmlibc/inline-function-decl.hpp
@@ -17,11 +17,13 @@
 
 constexpr long long addll(long long a, long long b) {
 // CHECK-MESSAGES: :[[@LINE-1]]:1: warning: 'addll' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
+// CHECK-FIXES: LIBC_INLINE constexpr long long addll(long long a, long long b) {
   return a + b;
 }
 
 inline unsigned long addul(unsigned long a, unsigned long b) {
 // CHECK-MESSAGES: :[[@LINE-1]]:1: warning: 'addul' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
+// CHECK-FIXES: LIBC_INLINE inline unsigned long addul(unsigned long a, unsigned long b) {
   return a + b;
 }
 
@@ -30,11 +32,13 @@
 public:
   MyClass() : A(123) {}
   // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'MyClass' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
+  // CHECK-FIXES:   LIBC_INLINE MyClass() : A(123) {}
 
   LIBC_INLINE MyClass(int V) : A(V) {}
 
   constexpr operator int() const { return A; }
   // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'operator int' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
+  // CHECK-FIXES:   LIBC_INLINE constexpr operator int() const { return A; }
 
   LIBC_INLINE bool operator==(const MyClass &RHS) {
     return RHS.A == A;
@@ -42,6 +46,7 @@
 
   static int getVal(const MyClass &V) {
   // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'getVal' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
+  // CHECK-FIXES:   LIBC_INLINE static int getVal(const MyClass &V) {
     return V.A;
   }
 
@@ -51,6 +56,7 @@
 
   constexpr static int addInt(MyClass &V, int A) {
   // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'addInt' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
+  // CHECK-FIXES:   LIBC_INLINE constexpr static int addInt(MyClass &V, int A) {
     return V.A += A;
   }
 
@@ -78,6 +84,7 @@
 
 inline void badSimpleFunction() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:1: warning: 'badSimpleFunction' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
+// CHECK-FIXES: LIBC_INLINE inline void badSimpleFunction() {}
 
 void LIBC_INLINE badSimpleFunctionWrongLocation() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:1: warning: 'badSimpleFunctionWrongLocation' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
@@ -93,6 +100,7 @@
 
 template <typename T> inline void badTemplateFunction() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:23: warning: 'badTemplateFunction' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
+// CHECK-FIXES: template <typename T> LIBC_INLINE inline void badTemplateFunction() {}
 
 template <typename T> void LIBC_INLINE badTemplateFunctionWrongLocation() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:23: warning: 'badTemplateFunctionWrongLocation' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
@@ -108,9 +116,11 @@
 
 template <typename... Ts> inline void badVariadicFunction() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:27: warning: 'badVariadicFunction' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
+// CHECK-FIXES: template <typename... Ts> LIBC_INLINE inline void badVariadicFunction() {}
 
 template <typename... Ts> void LIBC_INLINE badVariadicFunctionWrongLocation() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:27: warning: 'badVariadicFunctionWrongLocation' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
+// CHECK-FIXES: template <typename... Ts> LIBC_INLINE void LIBC_INLINE badVariadicFunctionWrongLocation() {}
 
 struct NoTemplate {
   void goodNoTemplate();
@@ -137,22 +147,27 @@
 
 inline void NoTemplate::badNoTemplate() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:1: warning: 'badNoTemplate' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
+// CHECK-FIXES: LIBC_INLINE inline void NoTemplate::badNoTemplate() {}
 
 void LIBC_INLINE NoTemplate::badNoTemplateWrongLocation() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:1: warning: 'badNoTemplateWrongLocation' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
+// CHECK-FIXES: LIBC_INLINE void LIBC_INLINE NoTemplate::badNoTemplateWrongLocation() {}
 
 template <typename T> LIBC_INLINE void NoTemplate::goodNestedTemplate() {}
 
 template <typename T> inline void NoTemplate::badNestedTemplate() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:23: warning: 'badNestedTemplate' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
+// CHECK-FIXES: template <typename T> LIBC_INLINE inline void NoTemplate::badNestedTemplate() {}
 
 template <typename T> void LIBC_INLINE NoTemplate::badNestedTemplateWrongLocation() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:23: warning: 'badNestedTemplateWrongLocation' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
+// CHECK-FIXES: template <typename T> LIBC_INLINE void LIBC_INLINE NoTemplate::badNestedTemplateWrongLocation() {}
 
 template <typename... Ts> LIBC_INLINE void NoTemplate::goodVariadicTemplate() {}
 
 template <typename... Ts> void inline NoTemplate::badVariadicTemplate() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:27: warning: 'badVariadicTemplate' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
+// CHECK-FIXES: template <typename... Ts> LIBC_INLINE void inline NoTemplate::badVariadicTemplate() {}
 
 template <typename... Ts> void LIBC_INLINE NoTemplate::badVariadicTemplateWrongLocation() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:27: warning: 'badVariadicTemplateWrongLocation' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
@@ -182,6 +197,7 @@
 
 template <typename T> inline void SimpleTemplate<T>::badSimpleTemplate() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:23: warning: 'badSimpleTemplate' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
+// CHECK-FIXES: template <typename T> LIBC_INLINE inline void SimpleTemplate<T>::badSimpleTemplate() {}
 
 template <typename T> void LIBC_INLINE SimpleTemplate<T>::badSimpleTemplateWrongLocation() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:23: warning: 'badSimpleTemplateWrongLocation' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
@@ -190,6 +206,7 @@
 
 template <typename T> template <typename U> inline void SimpleTemplate<T>::badNestedTemplate() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:45: warning: 'badNestedTemplate' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
+// CHECK-FIXES: template <typename T> template <typename U> LIBC_INLINE inline void SimpleTemplate<T>::badNestedTemplate() {}
 
 template <typename T> template <typename U> void LIBC_INLINE SimpleTemplate<T>::badNestedTemplateWrongLocation() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:45: warning: 'badNestedTemplateWrongLocation' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
@@ -198,6 +215,7 @@
 
 template <typename T> template <typename... Ts> inline void SimpleTemplate<T>::badNestedVariadicTemplate() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:49: warning: 'badNestedVariadicTemplate' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
+// CHECK-FIXES: template <typename T> template <typename... Ts> LIBC_INLINE inline void SimpleTemplate<T>::badNestedVariadicTemplate() {}
 
 template <typename T> template <typename... Ts> void LIBC_INLINE SimpleTemplate<T>::badNestedVariadicTemplateWrongLocation() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:49: warning: 'badNestedVariadicTemplateWrongLocation' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
@@ -227,6 +245,7 @@
 
 template <typename... Ts> inline void VariadicTemplate<Ts...>::badVariadicTemplate() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:27: warning: 'badVariadicTemplate' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
+// CHECK-FIXES: template <typename... Ts> LIBC_INLINE inline void VariadicTemplate<Ts...>::badVariadicTemplate() {}
 
 template <typename... Ts> void LIBC_INLINE VariadicTemplate<Ts...>::badVariadicTemplateWrongLocation() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:27: warning: 'badVariadicTemplateWrongLocation' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
@@ -235,6 +254,7 @@
 
 template <typename... Ts> template <typename U> inline void VariadicTemplate<Ts...>::badNestedTemplate() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:49: warning: 'badNestedTemplate' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
+// CHECK-FIXES: template <typename... Ts> template <typename U> LIBC_INLINE inline void VariadicTemplate<Ts...>::badNestedTemplate() {}
 
 template <typename... Ts> template <typename U> void LIBC_INLINE VariadicTemplate<Ts...>::badNestedTemplateWrongLocation() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:49: warning: 'badNestedTemplateWrongLocation' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
@@ -243,6 +263,7 @@
 
 template <typename... Ts> template <typename... Us> inline void VariadicTemplate<Ts...>::badNestedVariadicTemplate() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:53: warning: 'badNestedVariadicTemplate' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]
+// CHECK-FIXES: template <typename... Ts> template <typename... Us> LIBC_INLINE inline void VariadicTemplate<Ts...>::badNestedVariadicTemplate() {}
 
 template <typename... Ts> template <typename... Us> void LIBC_INLINE VariadicTemplate<Ts...>::badNestedVariadicTemplateWrongLocation() {}
 // CHECK-MESSAGES: :[[@LINE-1]]:53: warning: 'badNestedVariadicTemplateWrongLocation' must be tagged with the LIBC_INLINE macro; the macro should be placed at the beginning of the declaration [llvmlibc-inline-function-decl]