diff --git a/llvm/include/llvm/IR/RuntimeLibcalls.h b/llvm/include/llvm/IR/RuntimeLibcalls.h
index 26c085031a48a..89e466ee5933d 100644
--- a/llvm/include/llvm/IR/RuntimeLibcalls.h
+++ b/llvm/include/llvm/IR/RuntimeLibcalls.h
@@ -15,6 +15,7 @@
 #define LLVM_IR_RUNTIME_LIBCALLS_H
 
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/Sequence.h"
 #include "llvm/IR/CallingConv.h"
 #include "llvm/Support/AtomicOrdering.h"
 #include "llvm/Support/Compiler.h"
@@ -36,6 +37,18 @@ enum Libcall {
 #include "llvm/IR/RuntimeLibcalls.def"
 #undef HANDLE_LIBCALL
 };
+} // namespace RTLIB
+
+template <> struct enum_iteration_traits<RTLIB::Libcall> {
+  static constexpr bool is_iterable = true;
+};
+
+namespace RTLIB {
+
+// Return an iterator over all Libcall values.
+static inline auto libcalls() {
+  return enum_seq(static_cast<RTLIB::Libcall>(0), RTLIB::UNKNOWN_LIBCALL);
+}
 
 /// A simple container for information about the supported runtime calls.
 struct RuntimeLibcallsInfo {
diff --git a/llvm/lib/IR/RuntimeLibcalls.cpp b/llvm/lib/IR/RuntimeLibcalls.cpp
index ca45cd4b7b13c..0936c7cc64f37 100644
--- a/llvm/lib/IR/RuntimeLibcalls.cpp
+++ b/llvm/lib/IR/RuntimeLibcalls.cpp
@@ -208,21 +208,14 @@ void RuntimeLibcallsInfo::initLibcalls(const Triple &TT) {
     setLibcallName(RTLIB::FREXP_PPCF128, nullptr);
   }
 
-  // Disable most libcalls on AMDGPU.
-  if (TT.isAMDGPU()) {
-    for (int I = 0; I < RTLIB::UNKNOWN_LIBCALL; ++I) {
-      if (I < RTLIB::ATOMIC_LOAD || I > RTLIB::ATOMIC_FETCH_NAND_16)
-        setLibcallName(static_cast<RTLIB::Libcall>(I), nullptr);
+  // Disable most libcalls on AMDGPU and NVPTX.
+  if (TT.isAMDGPU() || TT.isNVPTX()) {
+    for (RTLIB::Libcall LC : RTLIB::libcalls()) {
+      if (LC < RTLIB::ATOMIC_LOAD || LC > RTLIB::ATOMIC_FETCH_NAND_16)
+        setLibcallName(LC, nullptr);
     }
   }
 
-  // Disable most libcalls on NVPTX.
-  if (TT.isNVPTX()) {
-    for (int I = 0; I < RTLIB::UNKNOWN_LIBCALL; ++I)
-      if (I < RTLIB::ATOMIC_LOAD || I > RTLIB::ATOMIC_FETCH_NAND_16)
-        setLibcallName(static_cast<RTLIB::Libcall>(I), nullptr);
-  }
-
   if (TT.isOSMSVCRT()) {
     // MSVCRT doesn't have powi; fall back to pow
     setLibcallName(RTLIB::POWI_F32, nullptr);
diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index d156851d7e214..574281d12e3cb 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -511,10 +511,11 @@ ARMTargetLowering::ARMTargetLowering(const TargetMachine &TM,
   if (!Subtarget->isTargetDarwin() && !Subtarget->isTargetIOS() &&
       !Subtarget->isTargetWatchOS() && !Subtarget->isTargetDriverKit()) {
     bool IsHFTarget = TM.Options.FloatABIType == FloatABI::Hard;
-    for (int LCID = 0; LCID < RTLIB::UNKNOWN_LIBCALL; ++LCID)
-      setLibcallCallingConv(static_cast<RTLIB::Libcall>(LCID),
-                            IsHFTarget ? CallingConv::ARM_AAPCS_VFP
-                                       : CallingConv::ARM_AAPCS);
+
+    for (RTLIB::Libcall LC : RTLIB::libcalls()) {
+      setLibcallCallingConv(LC, IsHFTarget ? CallingConv::ARM_AAPCS_VFP
+                                           : CallingConv::ARM_AAPCS);
+    }
   }
 
   if (Subtarget->isTargetMachO()) {
diff --git a/llvm/lib/Target/Lanai/LanaiISelLowering.cpp b/llvm/lib/Target/Lanai/LanaiISelLowering.cpp
index 8b50eb2678af6..7781817aef71a 100644
--- a/llvm/lib/Target/Lanai/LanaiISelLowering.cpp
+++ b/llvm/lib/Target/Lanai/LanaiISelLowering.cpp
@@ -151,9 +151,8 @@ LanaiTargetLowering::LanaiTargetLowering(const TargetMachine &TM,
   setMinimumJumpTableEntries(100);
 
   // Use fast calling convention for library functions.
-  for (int I = 0; I < RTLIB::UNKNOWN_LIBCALL; ++I) {
-    setLibcallCallingConv(static_cast<RTLIB::Libcall>(I), CallingConv::Fast);
-  }
+  for (RTLIB::Libcall LC : RTLIB::libcalls())
+    setLibcallCallingConv(LC, CallingConv::Fast);
 
   MaxStoresPerMemset = 16; // For @llvm.memset -> sequence of stores
   MaxStoresPerMemsetOptSize = 8;