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
@@ -2189,6 +2189,8 @@
   HelpText<"Specify the boundary's size to align branches">;
 def mpad_max_prefix_size_EQ : Joined<["-"], "mpad-max-prefix-size=">, Group<m_Group>, Flags<[DriverOption]>,
   HelpText<"Specify maximum number of prefixes to use for padding">;
+def malign_branch_prefix_size_EQ : Joined<["-"], "malign-branch-prefix-size=">, Group<m_Group>, Flags<[DriverOption]>, Alias<mpad_max_prefix_size_EQ>,
+  HelpText<"Alias for -mpad-max-prefix-size">;// Alias for GCC compatibility
 def mbranches_within_32B_boundaries : Flag<["-"], "mbranches-within-32B-boundaries">, Flags<[DriverOption]>, Group<m_Group>,
   HelpText<"Align selected branches (fused, jcc, jmp) within 32-byte boundary">;
 def mfancy_math_387 : Flag<["-"], "mfancy-math-387">, Group<clang_ignored_m_Group>;
diff --git a/clang/test/Driver/x86-malign-branch.c b/clang/test/Driver/x86-malign-branch.c
--- a/clang/test/Driver/x86-malign-branch.c
+++ b/clang/test/Driver/x86-malign-branch.c
@@ -24,6 +24,9 @@
 // RUN: %clang -target x86_64 -mpad-max-prefix-size=15 %s -c -### 2>&1 | FileCheck %s --check-prefix=PREFIX-15
 // PREFIX-15: "-mllvm" "-x86-pad-max-prefix-size=15"
 
+/// Test -malign-branch-prefix-size= for GCC compatibilty
+// RUN: %clang -target x86_64 -malign-branch-prefix-size=5 %s -c -### 2>&1 | FileCheck %s --check-prefix=PREFIX-5
+
 /// Test -mbranches-within-32B-boundaries
 // RUN: %clang -target x86_64 -mbranches-within-32B-boundaries %s -c -### 2>&1 | FileCheck %s --check-prefix=32B
 // 32B: "-mllvm" "-x86-branches-within-32B-boundaries"
diff --git a/clang/test/Driver/x86-malign-branch.s b/clang/test/Driver/x86-malign-branch.s
--- a/clang/test/Driver/x86-malign-branch.s
+++ b/clang/test/Driver/x86-malign-branch.s
@@ -9,5 +9,7 @@
 // RUN: %clang -target x86_64 -mpad-max-prefix-size=5 %s -c -### 2>&1 | FileCheck %s --check-prefix=PREFIX
 // PREFIX: "-mllvm" "-x86-pad-max-prefix-size=5"
 
+// RUN: %clang -target x86_64 -malign-branch-prefix-size=5 %s -c -### 2>&1 | FileCheck %s --check-prefix=PREFIX
+
 // RUN: %clang -target x86_64 -mbranches-within-32B-boundaries %s -c -### 2>&1 | FileCheck %s --check-prefix=32B
 // 32B: "-mllvm" "-x86-branches-within-32B-boundaries"