diff --git a/src/base/allocator/partition_allocator/partition_root.cc b/src/base/allocator/partition_allocator/partition_root.cc
index f061b2a3f9..5cfd16632d 100644
--- a/src/base/allocator/partition_allocator/partition_root.cc
+++ b/src/base/allocator/partition_allocator/partition_root.cc
@@ -239,7 +239,12 @@ void PartitionAllocMallocInitOnce() {
   if (!g_global_init_called.compare_exchange_strong(expected, true))
     return;
 
-#if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS)
+#if defined(__MUSL__)
+  // Musl calls malloc() in pthread_atfork(), resulting in a deadlock.
+  static_cast<void>(BeforeForkInParent);
+  static_cast<void>(AfterForkInParent);
+  static_cast<void>(AfterForkInChild);
+#elif BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS)
   // When fork() is called, only the current thread continues to execute in the
   // child process. If the lock is held, but *not* by this thread when fork() is
   // called, we have a deadlock.
diff --git a/src/base/allocator/partition_allocator/shim/allocator_shim_default_dispatch_to_partition_alloc.cc b/src/base/allocator/partition_allocator/shim/allocator_shim_default_dispatch_to_partition_alloc.cc
index 09716477b6..d291490785 100644
--- a/src/base/allocator/partition_allocator/shim/allocator_shim_default_dispatch_to_partition_alloc.cc
+++ b/src/base/allocator/partition_allocator/shim/allocator_shim_default_dispatch_to_partition_alloc.cc
@@ -759,7 +759,7 @@ SHIM_ALWAYS_EXPORT int mallopt(int cmd, int value) __THROW {
 
 #endif  // !BUILDFLAG(IS_APPLE) && !BUILDFLAG(IS_ANDROID)
 
-#if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS)
+#if BUILDFLAG(IS_LINUX) && !defined(__MUSL__) || BUILDFLAG(IS_CHROMEOS)
 SHIM_ALWAYS_EXPORT struct mallinfo mallinfo(void) __THROW {
   partition_alloc::SimplePartitionStatsDumper allocator_dumper;
   Allocator()->DumpStats("malloc", true, &allocator_dumper);
diff --git a/src/base/allocator/partition_allocator/shim/allocator_shim_internals.h b/src/base/allocator/partition_allocator/shim/allocator_shim_internals.h
index 8bddea78c3..d35e7a980d 100644
--- a/src/base/allocator/partition_allocator/shim/allocator_shim_internals.h
+++ b/src/base/allocator/partition_allocator/shim/allocator_shim_internals.h
@@ -9,7 +9,8 @@
 
 #if defined(__GNUC__)
 
-#if BUILDFLAG(IS_POSIX)
+// Musl does not provide sys/cdefs.h
+#if BUILDFLAG(IS_POSIX) && !defined(__MUSL__)
 #include <sys/cdefs.h>  // for __THROW
 #endif
 
diff --git a/src/base/allocator/partition_allocator/shim/allocator_shim_override_libc_symbols.h b/src/base/allocator/partition_allocator/shim/allocator_shim_override_libc_symbols.h
index bb07170019..49c305a9ac 100644
--- a/src/base/allocator/partition_allocator/shim/allocator_shim_override_libc_symbols.h
+++ b/src/base/allocator/partition_allocator/shim/allocator_shim_override_libc_symbols.h
@@ -22,6 +22,12 @@
 
 #include "base/allocator/partition_allocator/shim/allocator_shim_internals.h"
 
+// Musl does not specify anything for malloc() etc.
+#if defined(__MUSL__)
+#undef __THROW
+#define __THROW
+#endif
+
 extern "C" {
 
 // WARNING: Whenever a new function is added there (which, surprisingly enough,