diff --git a/include/clang/AST/Decl.h b/include/clang/AST/Decl.h
index 3cca66f..8b9688b 100644
--- a/include/clang/AST/Decl.h
+++ b/include/clang/AST/Decl.h
@@ -1887,7 +1887,7 @@
   /// \brief Determine whether this function should be inlined, because it is
   /// either marked "inline" or "constexpr" or is a member function of a class
   /// that was defined in the class body.
-  bool isInlined() const;
+  bool isInlined() const { return IsInline; }
 
   bool isInlineDefinitionExternallyVisible() const;
 
diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index 7a51814..6ecc2cc 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -1962,38 +1962,6 @@
   return NumRequiredArgs;
 }
 
-bool FunctionDecl::isInlined() const {
-  if (IsInline)
-    return true;
-  
-  if (isa<CXXMethodDecl>(this)) {
-    if (!isOutOfLine() || getCanonicalDecl()->isInlineSpecified())
-      return true;
-  }
-
-  switch (getTemplateSpecializationKind()) {
-  case TSK_Undeclared:
-  case TSK_ExplicitSpecialization:
-    return false;
-
-  case TSK_ImplicitInstantiation:
-  case TSK_ExplicitInstantiationDeclaration:
-  case TSK_ExplicitInstantiationDefinition:
-    // Handle below.
-    break;
-  }
-
-  const FunctionDecl *PatternDecl = getTemplateInstantiationPattern();
-  bool HasPattern = false;
-  if (PatternDecl)
-    HasPattern = PatternDecl->hasBody(PatternDecl);
-  
-  if (HasPattern && PatternDecl)
-    return PatternDecl->isInlined();
-  
-  return false;
-}
-
 static bool RedeclForcesDefC99(const FunctionDecl *Redecl) {
   // Only consider file-scope declarations in this test.
   if (!Redecl->getLexicalDeclContext()->isTranslationUnit())
@@ -2069,8 +2037,8 @@
   return FoundBody;
 }
 
-/// \brief For an inline function definition in C or C++, determine whether the 
-/// definition will be externally visible.
+/// \brief For an inline function definition in C, or for a gnu_inline function
+/// in C++, determine whether the definition will be externally visible.
 ///
 /// Inline function definitions are always available for inlining optimizations.
 /// However, depending on the language dialect, declaration specifiers, and
@@ -2114,6 +2082,10 @@
     return false;
   }
 
+  // The rest of this function is C-only.
+  assert(!Context.getLangOpts().CPlusPlus &&
+         "should not use C inline rules in C++");
+
   // C99 6.7.4p6:
   //   [...] If all of the file scope declarations for a function in a 
   //   translation unit include the inline function specifier without extern, 
diff --git a/lib/Sema/SemaTemplateInstantiateDecl.cpp b/lib/Sema/SemaTemplateInstantiateDecl.cpp
index b0935a5..b679d49 100644
--- a/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -1120,6 +1120,9 @@
                            D->isInlineSpecified(), D->hasWrittenPrototype(),
                            D->isConstexpr());
 
+  if (D->isInlined())
+    Function->setImplicitlyInline();
+
   if (QualifierLoc)
     Function->setQualifierInfo(QualifierLoc);
 
@@ -1485,6 +1488,9 @@
                                    D->isConstexpr(), D->getLocEnd());
   }
 
+  if (D->isInlined())
+    Method->setImplicitlyInline();
+
   if (QualifierLoc)
     Method->setQualifierInfo(QualifierLoc);
 
@@ -2763,6 +2769,9 @@
       !PatternDecl->isInlined())
     return;
 
+  if (PatternDecl->isInlined())
+    Function->setImplicitlyInline();
+
   InstantiatingTemplate Inst(*this, PointOfInstantiation, Function);
   if (Inst)
     return;