diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -3009,7 +3009,6 @@
   HelpText<"Specify bit size of immediate TLS offsets (AArch64 ELF only): "
            "12 (for 4KB) | 24 (for 16MB, default) | 32 (for 4GB) | 48 (for 256TB, needs -mcmodel=large)">,
   MarshallingInfoInt<CodeGenOpts<"TLSSize">>;
-def mimplicit_it_EQ : Joined<["-"], "mimplicit-it=">, Group<m_Group>;
 def mdefault_build_attributes : Joined<["-"], "mdefault-build-attributes">, Group<m_Group>;
 def mno_default_build_attributes : Joined<["-"], "mno-default-build-attributes">, Group<m_Group>;
 def mconstant_cfstrings : Flag<["-"], "mconstant-cfstrings">, Group<clang_ignored_m_Group>;
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -2393,22 +2393,6 @@
                    DefaultIncrementalLinkerCompatible))
     CmdArgs.push_back("-mincremental-linker-compatible");
 
-  switch (C.getDefaultToolChain().getArch()) {
-  case llvm::Triple::arm:
-  case llvm::Triple::armeb:
-  case llvm::Triple::thumb:
-  case llvm::Triple::thumbeb:
-    if (Arg *A = Args.getLastArg(options::OPT_mimplicit_it_EQ)) {
-      StringRef Value = A->getValue();
-      if (!AddARMImplicitITArgs(Args, CmdArgs, Value))
-        D.Diag(diag::err_drv_unsupported_option_argument)
-            << A->getOption().getName() << Value;
-    }
-    break;
-  default:
-    break;
-  }
-
   // If you add more args here, also add them to the block below that
   // starts with "// If CollectArgsForIntegratedAssembler() isn't called below".
 
@@ -4353,16 +4337,6 @@
       Args.ClaimAllArgs(options::OPT_mno_relax_all);
       Args.ClaimAllArgs(options::OPT_mincremental_linker_compatible);
       Args.ClaimAllArgs(options::OPT_mno_incremental_linker_compatible);
-      switch (C.getDefaultToolChain().getArch()) {
-      case llvm::Triple::arm:
-      case llvm::Triple::armeb:
-      case llvm::Triple::thumb:
-      case llvm::Triple::thumbeb:
-        Args.ClaimAllArgs(options::OPT_mimplicit_it_EQ);
-        break;
-      default:
-        break;
-      }
     }
     Args.ClaimAllArgs(options::OPT_Wa_COMMA);
     Args.ClaimAllArgs(options::OPT_Xassembler);
diff --git a/clang/test/Driver/arm-implicit-it.s b/clang/test/Driver/arm-implicit-it.s
deleted file mode 100644
--- a/clang/test/Driver/arm-implicit-it.s
+++ /dev/null
@@ -1,24 +0,0 @@
-// RUN: %clang -target armv7--none-eabi -### %s 2>&1 \
-// RUN:    | FileCheck %s -check-prefix CHECK-DEFAULT
-
-// RUN: %clang -target armv7--none-eabi -mimplicit-it=arm -### %s 2>&1 \
-// RUN:    | FileCheck %s -check-prefix CHECK-ARM
-
-// RUN: %clang -target armv7--none-eabi -mimplicit-it=thumb -### %s 2>&1 \
-// RUN:    | FileCheck %s -check-prefix CHECK-THUMB
-
-// RUN: %clang -target armv7--none-eabi -mimplicit-it=never -### %s 2>&1 \
-// RUN:    | FileCheck %s -check-prefix CHECK-NEVER
-
-// RUN: %clang -target armv7--none-eabi -mimplicit-it=always -### %s 2>&1 \
-// RUN:    | FileCheck %s -check-prefix CHECK-ALWAYS
-
-// RUN: %clang -target armv7--none-eabi -mimplicit-it=thisisnotavalidoption -### %s 2>&1 \
-// RUN:    | FileCheck %s -check-prefix CHECK-INVALID
-
-// CHECK-DEFAULT-NOT: "-arm-implicit-it
-// CHECK-ARM: "-arm-implicit-it=arm"
-// CHECK-THUMB: "-arm-implicit-it=thumb"
-// CHECK-NEVER: "-arm-implicit-it=never"
-// CHECK-ALWAYS: "-arm-implicit-it=always"
-// CHECK-INVALID: error: unsupported argument 'thisisnotavalidoption' to option 'mimplicit-it='
diff --git a/clang/test/Driver/arm-target-as-mimplicit-it.s b/clang/test/Driver/arm-target-as-mimplicit-it.s
--- a/clang/test/Driver/arm-target-as-mimplicit-it.s
+++ b/clang/test/Driver/arm-target-as-mimplicit-it.s
@@ -20,13 +20,6 @@
 // RUN: %clang -target arm-linux-gnueabi -### -Wa,-mimplicit-it=always,-mimplicit-it=arm %s 2>&1 | FileCheck %s --check-prefix=ARM
 // RUN: %clang -target arm-linux-gnueabi -### -Wa,-mimplicit-it=always,-mimplicit-it=thumb %s 2>&1 | FileCheck %s --check-prefix=THUMB
 
-/// Mix -implicit-it= (compiler) with -Wa,-mimplicit-it= (assembler), assembler
-/// takes priority. -mllvm -arm-implicit-it= will be repeated, with the
-/// assembler flag appearing last (latter wins).
-// RUN: %clang -target arm-linux-gnueabi -### -mimplicit-it=never -Wa,-mimplicit-it=always %S/Inputs/wildcard1.c 2>&1 | FileCheck %s --check-prefix=NEVER_ALWAYS
-// RUN: %clang -target arm-linux-gnueabi -### -mimplicit-it=always -Wa,-mimplicit-it=never %S/Inputs/wildcard1.c 2>&1 | FileCheck %s --check-prefix=ALWAYS_NEVER
-// RUN: %clang -target arm-linux-gnueabi -### -Wa,-mimplicit-it=never -mimplicit-it=always %S/Inputs/wildcard1.c 2>&1 | FileCheck %s --check-prefix=ALWAYS_NEVER
-
 /// Test invalid input.
 // RUN: %clang -target arm-linux-gnueabi -### -Wa,-mimplicit-it=foo %s 2>&1 | FileCheck %s --check-prefix=INVALID
 // RUN: %clang -target arm-linux-gnueabi -### -Xassembler -mimplicit-it=foo %s 2>&1 | FileCheck %s --check-prefix=XINVALID
@@ -38,7 +31,5 @@
 // NEVER: "-mllvm" "-arm-implicit-it=never"
 // ARM: "-mllvm" "-arm-implicit-it=arm"
 // THUMB: "-mllvm" "-arm-implicit-it=thumb"
-// NEVER_ALWAYS: "-mllvm" "-arm-implicit-it=never" "-mllvm" "-arm-implicit-it=always"
-// ALWAYS_NEVER: "-mllvm" "-arm-implicit-it=always" "-mllvm" "-arm-implicit-it=never"
 // INVALID: error: unsupported argument '-mimplicit-it=foo' to option 'Wa,'
 // XINVALID: error: unsupported argument '-mimplicit-it=foo' to option 'Xassembler'
diff --git a/clang/test/Driver/as-options.s b/clang/test/Driver/as-options.s
--- a/clang/test/Driver/as-options.s
+++ b/clang/test/Driver/as-options.s
@@ -53,20 +53,6 @@
 // RUN:   -o /dev/null -x assembler-with-cpp %s 2>&1 \
 // RUN:   | FileCheck --check-prefix=WARN --allow-empty %s
 
-// RUN: %clang -mimplicit-it=always -target armv7-linux-gnueabi -E \
-// RUN:   -fintegrated-as -o /dev/null -x c++ %s 2>&1 \
-// RUN:   | FileCheck --check-prefix=NOWARN --allow-empty %s
-// RUN: %clang -mimplicit-it=always -target armv7-linux-gnueabi -E \
-// RUN:   -fno-integrated-as -o /dev/null -x c++ %s 2>&1 \
-// RUN:   | FileCheck --check-prefix=WARN --allow-empty %s
-
-// RUN: %clang -mimplicit-it=always -target armv7-linux-gnueabi -E \
-// RUN:   -fintegrated-as -o /dev/null -x assembler-with-cpp %s 2>&1 \
-// RUN:   | FileCheck --check-prefix=NOWARN --allow-empty %s
-// RUN: %clang -mimplicit-it=always -target armv7-linux-gnueabi -E \
-// RUN:   -fno-integrated-as -o /dev/null -x assembler-with-cpp %s 2>&1 \
-// RUN:   | FileCheck --check-prefix=WARN --allow-empty %s
-
 // RUN: %clang -Wa,-mbig-obj -target i386-pc-windows -E -fintegrated-as \
 // RUN:   -o /dev/null -x c++ %s 2>&1 \
 // RUN:   | FileCheck --check-prefix=NOWARN --allow-empty %s