diff --git a/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp b/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
index 70035bd0975d0..8e864878b42b0 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
@@ -474,7 +474,13 @@ bool RISCVPassConfig::addPreISel() {
     addPass(createBarrierNoopPass());
   }
 
-  if (EnableGlobalMerge == cl::BOU_TRUE) {
+  if ((TM->getOptLevel() != CodeGenOptLevel::None &&
+       EnableGlobalMerge == cl::BOU_UNSET) ||
+      EnableGlobalMerge == cl::BOU_TRUE) {
+    // FIXME: Like AArch64, we disable extern global merging by default due to
+    // concerns it might regress some workloads. Unlike AArch64, we don't
+    // currently support enabling the pass in an "OnlyOptimizeForSize" mode.
+    // Investigating and addressing both items are TODO.
     addPass(createGlobalMergePass(TM, /* MaxOffset */ 2047,
                                   /* OnlyOptimizeForSize */ false,
                                   /* MergeExternalByDefault */
diff --git a/llvm/test/CodeGen/RISCV/O3-pipeline.ll b/llvm/test/CodeGen/RISCV/O3-pipeline.ll
index a74c842c59552..8fd9ae9850366 100644
--- a/llvm/test/CodeGen/RISCV/O3-pipeline.ll
+++ b/llvm/test/CodeGen/RISCV/O3-pipeline.ll
@@ -74,6 +74,7 @@
 ; CHECK-NEXT:       Exception handling preparation
 ; CHECK-NEXT:     A No-Op Barrier Pass
 ; CHECK-NEXT:     FunctionPass Manager
+; CHECK-NEXT:       Merge internal globals
 ; CHECK-NEXT:       Dominator Tree Construction
 ; CHECK-NEXT:       Basic Alias Analysis (stateless AA impl)
 ; CHECK-NEXT:       Function Alias Analysis Results
diff --git a/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-nonzero.ll b/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-nonzero.ll
index 39c677ac20b3a..156a34db82745 100644
--- a/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-nonzero.ll
+++ b/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-nonzero.ll
@@ -1,7 +1,7 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv64 -riscv-enable-global-merge -riscv-force-enable-global-merge-external-globals \
+; RUN: llc -mtriple=riscv64 -riscv-force-enable-global-merge-external-globals \
 ; RUN:   -verify-machineinstrs < %s | FileCheck %s -check-prefix=SMALL-DATA
-; RUN: llc -mtriple=riscv64 -riscv-enable-global-merge -global-merge-min-data-size=0 \
+; RUN: llc -mtriple=riscv64 -global-merge-min-data-size=0 \
 ; RUN:   -riscv-force-enable-global-merge-external-globals -verify-machineinstrs < %s \
 ; RUN:   | FileCheck %s -check-prefix=MINSIZE
 
diff --git a/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-zero.ll b/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-zero.ll
index d2b714577db9a..e41f14d394b7c 100644
--- a/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-zero.ll
+++ b/llvm/test/CodeGen/RISCV/global-merge-minsize-smalldata-zero.ll
@@ -1,7 +1,7 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv32 -riscv-enable-global-merge -riscv-force-enable-global-merge-external-globals \
+; RUN: llc -mtriple=riscv32 -riscv-force-enable-global-merge-external-globals \
 ; RUN:   -verify-machineinstrs < %s | FileCheck %s -check-prefix=SMALL-DATA
-; RUN: llc -mtriple=riscv64 -riscv-enable-global-merge -global-merge-min-data-size=5 \
+; RUN: llc -mtriple=riscv64 -global-merge-min-data-size=5 \
 ; RUN:   -riscv-force-enable-global-merge-external-globals  -verify-machineinstrs < %s \
 ; RUN:   | FileCheck %s -check-prefix=MINSIZE
 
diff --git a/llvm/test/CodeGen/RISCV/global-merge-minsize.ll b/llvm/test/CodeGen/RISCV/global-merge-minsize.ll
index 696d163bdcb2c..1d65d9d1732ba 100644
--- a/llvm/test/CodeGen/RISCV/global-merge-minsize.ll
+++ b/llvm/test/CodeGen/RISCV/global-merge-minsize.ll
@@ -1,7 +1,7 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv32 -riscv-enable-global-merge -riscv-force-enable-global-merge-external-globals \
+; RUN: llc -mtriple=riscv32 -riscv-force-enable-global-merge-external-globals \
 ; RUN:   -verify-machineinstrs < %s | FileCheck %s -check-prefix=RV32
-; RUN: llc -mtriple=riscv32 -riscv-enable-global-merge -global-merge-min-data-size=5 \
+; RUN: llc -mtriple=riscv32 -global-merge-min-data-size=5 \
 ; RUN:   -riscv-force-enable-global-merge-external-globals -verify-machineinstrs < %s | FileCheck %s -check-prefix=RV32-MINSIZE
 
 @ig1 = internal global i32 0, align 4
diff --git a/llvm/test/CodeGen/RISCV/global-merge-offset.ll b/llvm/test/CodeGen/RISCV/global-merge-offset.ll
index 0c0881ddf2873..bb8264ee43854 100644
--- a/llvm/test/CodeGen/RISCV/global-merge-offset.ll
+++ b/llvm/test/CodeGen/RISCV/global-merge-offset.ll
@@ -1,11 +1,11 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: sed 's/ArrSize/100/g' %s | llc -mtriple=riscv32 -riscv-enable-global-merge \
+; RUN: sed 's/ArrSize/100/g' %s | llc -mtriple=riscv32 \
 ; RUN:   -riscv-force-enable-global-merge-external-globals -verify-machineinstrs | FileCheck %s
-; RUN: sed 's/ArrSize/100/g' %s | llc -mtriple=riscv64 -riscv-enable-global-merge \
+; RUN: sed 's/ArrSize/100/g' %s | llc -mtriple=riscv64 \
 ; RUN:   -riscv-force-enable-global-merge-external-globals -verify-machineinstrs | FileCheck %s
-; RUN: sed 's/ArrSize/101/g' %s | llc -mtriple=riscv32 -riscv-enable-global-merge \
+; RUN: sed 's/ArrSize/101/g' %s | llc -mtriple=riscv32 \
 ; RUN:   -riscv-force-enable-global-merge-external-globals -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-TOOBIG
-; RUN: sed 's/ArrSize/101/g' %s | llc -mtriple=riscv64 -riscv-enable-global-merge \
+; RUN: sed 's/ArrSize/101/g' %s | llc -mtriple=riscv64 \
 ; RUN:   -riscv-force-enable-global-merge-external-globals -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-TOOBIG
 
 ; This test demonstrates that the MaxOffset is set correctly for RISC-V by
diff --git a/llvm/test/CodeGen/RISCV/global-merge.ll b/llvm/test/CodeGen/RISCV/global-merge.ll
index 633ba719c6a30..8b4043ed476f7 100644
--- a/llvm/test/CodeGen/RISCV/global-merge.ll
+++ b/llvm/test/CodeGen/RISCV/global-merge.ll
@@ -1,12 +1,10 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv32 -riscv-enable-global-merge -verify-machineinstrs < %s \
-; RUN:   | FileCheck %s
-; RUN: llc -mtriple=riscv64 -riscv-enable-global-merge -verify-machineinstrs < %s \
-; RUN:   | FileCheck %s
-; RUN: llc -mtriple=riscv32 -riscv-enable-global-merge \
+; RUN: llc -mtriple=riscv32 -verify-machineinstrs < %s | FileCheck %s
+; RUN: llc -mtriple=riscv64 -verify-machineinstrs < %s | FileCheck %s
+; RUN: llc -mtriple=riscv32 \
 ; RUN:     -riscv-force-enable-global-merge-external-globals -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=CHECK-WEXTERN %s
-; RUN: llc -mtriple=riscv64 -riscv-enable-global-merge \
+; RUN: llc -mtriple=riscv64 \
 ; RUN:     -riscv-force-enable-global-merge-external-globals -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=CHECK-WEXTERN %s