Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp
+++ lib/Sema/SemaExpr.cpp
@@ -1373,10 +1373,13 @@
 
   // Decay and strip qualifiers for the controlling expression type, and handle
   // placeholder type replacement. See committee discussion from WG14 DR423.
-  ExprResult R = DefaultFunctionArrayLvalueConversion(ControllingExpr);
-  if (R.isInvalid())
-    return ExprError();
-  ControllingExpr = R.get();
+  {
+    EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
+    ExprResult R = DefaultFunctionArrayLvalueConversion(ControllingExpr);
+    if (R.isInvalid())
+      return ExprError();
+    ControllingExpr = R.get();
+  }
 
   // The controlling expression is an unevaluated operand, so side effects are
   // likely unintended.
Index: test/Sema/generic-selection.c
===================================================================
--- test/Sema/generic-selection.c
+++ test/Sema/generic-selection.c
@@ -31,4 +31,8 @@
 
   const int i = 12;
   int a9[_Generic(i, int: 1, default: 2) == 1 ? 1 : -1];
+
+  // This is expected to not trigger any diagnostics because the controlling
+  // expression is not evaluated.
+  (void)_Generic(*(int *)0, int: 1);
 }