Index: ELF/Relocations.h
===================================================================
--- ELF/Relocations.h
+++ ELF/Relocations.h
@@ -73,6 +73,23 @@
   R_TLSLD_PC,
 };
 
+// Base case.
+constexpr uint64_t buildRelExprMask() { return 0; }
+// Build a bitmask with one bit set for each RelExpr.
+template <typename... RelExprs>
+constexpr uint64_t buildRelExprMask(RelExpr Head, RelExprs... Tail) {
+  return (uint64_t(1) << Head) | buildRelExprMask(Tail...);
+}
+
+// Return true if `Expr` is one of `Exprs`.
+// There are fewer than 64 RelExpr's, so we can represent any set of
+// RelExpr's as a constexpr bit mask and test for membership with a
+// couple cheap bitwise operations.
+template <typename... RelExprs>
+bool isRelExprOneOf(RelExpr Expr, RelExprs... Exprs) {
+  return (uint64_t(1) << Expr) & buildRelExprMask(Exprs...);
+}
+
 // Architecture-neutral representation of relocation.
 struct Relocation {
   RelExpr Expr;
Index: ELF/Relocations.cpp
===================================================================
--- ELF/Relocations.cpp
+++ ELF/Relocations.cpp
@@ -62,12 +62,10 @@
 namespace elf {
 
 static bool refersToGotEntry(RelExpr Expr) {
-  return Expr == R_GOT || Expr == R_GOT_OFF || Expr == R_MIPS_GOT_LOCAL_PAGE ||
-         Expr == R_MIPS_GOT_OFF || Expr == R_MIPS_GOT_OFF32 ||
-         Expr == R_MIPS_TLSGD || Expr == R_MIPS_TLSLD ||
-         Expr == R_GOT_PAGE_PC || Expr == R_GOT_PC || Expr == R_GOT_FROM_END ||
-         Expr == R_TLSGD || Expr == R_TLSGD_PC || Expr == R_TLSDESC ||
-         Expr == R_TLSDESC_PAGE;
+  return isRelExprOneOf(Expr, R_GOT, R_GOT_OFF, R_MIPS_GOT_LOCAL_PAGE,
+                        R_MIPS_GOT_OFF, R_MIPS_GOT_OFF32, R_MIPS_TLSGD,
+                        R_MIPS_TLSLD, R_GOT_PAGE_PC, R_GOT_PC, R_GOT_FROM_END,
+                        R_TLSGD, R_TLSGD_PC, R_TLSDESC, R_TLSDESC_PAGE);
 }
 
 static bool isPreemptible(const SymbolBody &Body, uint32_t Type) {
@@ -291,16 +289,15 @@
 }
 
 static bool needsPlt(RelExpr Expr) {
-  return Expr == R_PLT_PC || Expr == R_PPC_PLT_OPD || Expr == R_PLT ||
-         Expr == R_PLT_PAGE_PC || Expr == R_THUNK_PLT_PC;
+  return isRelExprOneOf(Expr, R_PLT_PC, R_PPC_PLT_OPD, R_PLT, R_PLT_PAGE_PC,
+                        R_THUNK_PLT_PC);
 }
 
 // True if this expression is of the form Sym - X, where X is a position in the
 // file (PC, or GOT for example).
 static bool isRelExpr(RelExpr Expr) {
-  return Expr == R_PC || Expr == R_GOTREL || Expr == R_GOTREL_FROM_END ||
-         Expr == R_MIPS_GOTREL || Expr == R_PAGE_PC || Expr == R_RELAX_GOT_PC ||
-         Expr == R_THUNK_PC || Expr == R_THUNK_PLT_PC;
+  return isRelExprOneOf(Expr, R_PC, R_GOTREL, R_GOTREL_FROM_END, R_MIPS_GOTREL,
+                        R_PAGE_PC, R_RELAX_GOT_PC, R_THUNK_PC, R_THUNK_PLT_PC);
 }
 
 template <class ELFT>
@@ -309,12 +306,11 @@
                                      InputSectionBase<ELFT> &S,
                                      typename ELFT::uint RelOff) {
   // These expressions always compute a constant
-  if (E == R_SIZE || E == R_GOT_FROM_END || E == R_GOT_OFF ||
-      E == R_MIPS_GOT_LOCAL_PAGE || E == R_MIPS_GOT_OFF ||
-      E == R_MIPS_GOT_OFF32 || E == R_MIPS_TLSGD || E == R_GOT_PAGE_PC ||
-      E == R_GOT_PC || E == R_PLT_PC || E == R_TLSGD_PC || E == R_TLSGD ||
-      E == R_PPC_PLT_OPD || E == R_TLSDESC_CALL || E == R_TLSDESC_PAGE ||
-      E == R_HINT || E == R_THUNK_PC || E == R_THUNK_PLT_PC)
+  if (isRelExprOneOf(E, R_SIZE, R_GOT_FROM_END, R_GOT_OFF,
+                     R_MIPS_GOT_LOCAL_PAGE, R_MIPS_GOT_OFF, R_MIPS_GOT_OFF32,
+                     R_MIPS_TLSGD, R_GOT_PAGE_PC, R_GOT_PC, R_PLT_PC,
+                     R_TLSGD_PC, R_TLSGD, R_PPC_PLT_OPD, R_TLSDESC_CALL,
+                     R_TLSDESC_PAGE, R_HINT, R_THUNK_PC, R_THUNK_PLT_PC))
     return true;
 
   // These never do, except if the entire file is position dependent or if
@@ -648,12 +644,12 @@
 
     // Ignore "hint" and TLS Descriptor call relocation because they are
     // only markers for relaxation.
-    if (Expr == R_HINT || Expr == R_TLSDESC_CALL)
+    if (isRelExprOneOf(Expr, R_HINT, R_TLSDESC_CALL))
       continue;
 
-    if (needsPlt(Expr) || Expr == R_THUNK_ABS || Expr == R_THUNK_PC ||
-        Expr == R_THUNK_PLT_PC || refersToGotEntry(Expr) ||
-        !isPreemptible(Body, Type)) {
+    if (needsPlt(Expr) ||
+        isRelExprOneOf(Expr, R_THUNK_ABS, R_THUNK_PC, R_THUNK_PLT_PC) ||
+        refersToGotEntry(Expr) || !isPreemptible(Body, Type)) {
       // If the relocation points to something in the file, we can process it.
       bool Constant =
           isStaticLinkTimeConstant<ELFT>(Expr, Type, Body, C, RI.r_offset);